If it’s just beauty, platonically, then do you also find yourself moved by and wanting to compliment attractive men?
Straight men generally don’t find other men attractive, IME, although I suppose there’s some element of fear-of-being-labelled-as-gay acting there.
Personally, I don’t have a problem telling another guy he’s got a good body, but I don’t think I’ve ever looked at another man’s face and thought, “Hey, he’s cute.” My brain just isn’t wired that way, and I think it’s the same for most men.
There’s a very good reason why there are tons of (straight) women who’ve kissed other women, and not nearly as many straight men who have (or would) kiss other men- we’re hairy and smell like dead fish, and you [global you] are less hairy and dainty and smell like strawberries.
How could you tell? Would their soul still shine so brightly if they turned around and told you where to go? If the place wasn’t too nice?
How can you know that you’re giving them a spark of cheer? Perhaps they had just been told by someone else that their beauty is their only attribute, and now you’re just rubbing their nose in it. That might not make them feel so cheerful.
They’re not objects; they’re people.
All of that said, there’s a time and a place, and it certainly can’t be generalized over a message board in a single thread when the right time and place would be to compliment someone sincerely and have them be happy about it.
And I’ve thought about it too. I still remember this woman who looked to be in her mid-80’s. She was wonderfully vibrant, sitting with her husband. They both were very cordial to me while we were waiting for our take-out food at a restaurant. She had the most beautiful blue eyes I’ve ever seen. And I really wanted to tell her that. But didn’t. This happened many months ago and I still think about it.
I’m female, btw.
ETA:
Egad! You smell like dead fish?! 
I was sitting in a McDonald’s in Quebec a few years ago with a (very pretty) friend, when a man walked past our table, leaned over, and said to my friend, “I just wanted to tell you that you’re very beautiful,” and left. But he didn’t quite get to the door before I burst out laughing. I shouldn’t have, he had just bared his soul a bit, and anyways it’s not so outlandish to find my friend beautiful. But it was a little strange. Or maybe I was just jealous, because no one would ever say that to me.
(Also, he spoke in English, which kind of implies he had been listening to us. He might have been sitting in the booth behind, in which case he couldn’t help overhearing, but still.)
Other men smell like dead fish. I smell like lilacs.
That’s not how it is for most women, either. It’s more “God, I wish I was as beautiful as she is” than that.
Soul Brother Number Two, a wistful smile at them is likely to be more appriciated than a comment. You’ll both know why you smiled, and no one gets creeped out 99% of the time.
That’s just the point- you’re able to make a value judgment (wow, she’s beautiful!) that we can’t. We don’t even want to look like Hot Guy X unless every chick we know thinks he’s dreamy, and then only because we’d get every chick we know*, because we (well, I) can’t tell if a man is handsome or not. I can identify ugly, but not handsome.
Unless you’re missing lots of teeth.
*in theory.
Okay, this anecdote is only tangentially related, but it is kinda funny, so what the heck…
BACKGROUND: When they were both in their 20s and 30s, my father was often mistaken for Paul Newman. He once got to sit in first class on an airplane with ZsaZsa Gabor, because she mistook him for Paul, and when she realized her mistake she said “never mind, come sit and talk with me during the flight, dahling.” There were also times when people got angry with him, because they were CONVINCED he really was Paul Newman, being an ass and denying his identity.
So…one day when I was an attractive girl in my early 20s, I saw a man on the street who looked eerily like my dad (the Paul Newman look-alike phenomenon had faded by then). Because of the strong resemblance, and the family jokes about my dad looking like someone else, I unthinkingly looked straight at the man and broke into a very warm smile.
Realizing that it probably seemed weird or like I was coming on to the guy, I walked up to him and said "oh, I’m so sorry to be eyeing you that way. It’s just that …
you look so much like my father."
I didn’t think anything of it at the time (oh callous youth) but in retrospect … I’ll bet that wasn’t what he hoped I’d be saying.
Yeah, a nice smile is the safest bet. It’s sad that saying something about it would be construed as creepy, but there it is.
This is not a brag–it’s an anecdote I’m sharing to illustrate the point:
I was walking with some friends, and a couple of guys drove by. They stopped, turned around and pulled up next to us to say that they thought we were gorgeous, were so glad we were walking down the street when they happened to drive by, etc.
It made me uncomfortable. It seemed creepy, and I didn’t like it that we still had to walk all the way home. The guys didn’t stalk us or do anything overt–they just stopped to give us a compliment. But it wasn’t welcome. A honk and a wave would have been plenty.
Oh, dear. Yeah, keep that to yourself. A smile and a nod is much more likely to get you a positive reaction than telling a strange woman half your age that you want to gaze upon her beauteous visage an instant longer, or anything remotely similar to that.
I complement people pretty frequently if I have reason to be speaking to them in the first place. But there is something about approaching a stranger solely to tell them “your beautiful” that comes across as a bit sinister and/or desperate, depending on the delivery. But a brief smile and eye contact is inoffensive.
Shoot. I’m not even sure if age has a lot to do with it.
I remeber back when I was a handome 24/25yo. I was at the Houston airport. I had to ride one of these tram things to get from one terminal to the next. It was very crowded, standing room only.
In front of me were these two gorgeous twins. I’m going to say they were about 16yo. They had the most beautiful green eyes I’ve ever seen in my life.
I told them this and they were clearly creeped out by it.
I don’t mean to toot my own horn or anything but this happened back in my twenties. I was quite the looker back then. (or so I’ve been told) Never had any problems get’n dates. Even so; I STILL managed to creep these girls out.
No way in hell would I try that these days.
I have often felt the same way as the Op, but not for any altruistic reason. A few times I have wanted to tell a strange woman that she was stunningly beautiful, but only because it would make me feel better having expressed it, like most any heartfelt emotion does.
I have never acted upon this desire though.
And you know this because. . . you go around smelling other men?
You might want to stop digging. It’s plenty deep already. 
I thought the accepted method was the slow grin and a Freddie Boom-Boom Washingtonesque “Daaaayum!”
No? Maybe just a regional thing?
Okay, I am a young woman in my 20’s and I’m going to go a bit against the grain here. Unknown older men (and women!) frequently tell me that I am beautiful. As long as the men don’t make any attempt to follow me (some have), I don’t find this threatening or creepy. I once smiled at a homeless man and he said, “Thank you, beautiful lady, you made my day.”
On the other hand, if a younger man were to walk up and say I was beautiful, I would indeed find this creepy, as I would immediately suspect some ulterior pants-getting-into type motive. However, a strange young man has never done this! It’s always older men! My friends have even noticed this phenomenon surrounding me.
I’m with Pyper, done correctly this sort of thing can make my day. I once left a gap between my car and the one stopped in front of me so a guy could pull out of the parking lot to my right, and he blew me a kiss. I still grin at the memory.
Try this: cultivate the Melvyn Douglas dapper old gent look, with fedora and bow tie. Practice your Maurice Chevalier impersonation, and when the moment presents itself, sweep the hat over your heart and break into “Thahng heaben fodor ladle gels!” (Of course, I live in Austin, that kind of spontaneous public performance art is expected around here.)
It’s not a drag, it’s creepy, and at best it would irritate me. At worst I’d tell you exactly how creepy and obnoxious I think you are.
Seriously? Are you seriously asking if there’s a way to walk up to a total stranger twenty years younger than you, ogle her, and you think it’s going to cheer her up?
If some random forty-year-old leering dude walked up to me and made some comment about my body, face, hair, eyes, whatever, I’d be extremely inclined to kick them in the nads. I’m not here for your viewing pleasure, you freak. Keep your eyes and your perverted comments to yourself.
Don’t sugar coat it. Tell him how you really feel.
From my observations, attractive females do not like being acknowledged as attractive, except by other attractive people. Unless you happen to be a hot guy yourself, expect an “ick” more often than a “thank you”.
Why do you feel the need to compliment a stranger on her looks? I’m not being sarcastic. I’ve noticed plenty of attractive men and women and I’ve never felt the desire to go up to them and say I thought they were attractive. I just don’t even get the point.
Like Really Not All That Bright said, they probably know already. And if for whatever reason they are unaware of their attractiveness, then a creepy stranger coming up is more likely to make them feel that they’re being hit on or otherwise being messed with. I know this from personal experience. Also, complimenting someone on something like her looks, for which she can only take a small part of the credit (genetics, etc being the primary factor), doesn’t make sense to me in the way that complimenting someone for a good deed does.