Once, a long time ago, when I worked in a hospital as a medical technician, I used to help train orderlies. It was not unusual for those wishing to pursue a career in medicine to work as an orderly or aid for a summer or so to determine if they really wanted to go into the field. I trained a guy who was going to medical school to be a doctor and later found out that he hoped that he would turn out just like me. I was very flattered. (No, a med tech is not a doctor or a nurse.)
I’d just like to say that the “but cannot prove” portion of the OP seems extremely strange to me. ** Sleestak, ** are your friends and family in the habit of laying claim to compliments which prove to be false? 
Dalia Carella made a point of telling me how much she liked my performance when I performed at her workshop hafla.
In the weird but provable category: After another show where I performed, I was standing around talking with some friends. This guy walked up to our group, kissed me, and continued onward with his girlfriend. I can only conclude that he did it because he was so moved by my performance.
AHunter3,
Nope, I think there was a “Purple something or other” down the street.
Stoid,
Nope. It’s just that having a NY Times food critic saying that I, a shmuck making 8 bucks an hour running a Mom and Mom coffee shop at the time, made the best salad she ever had is a little more than an average compliment.
Slee
Heh.
Read the sig.
Well, my ex-girlfriend once said that I was “the best bang since the big one” – I turned her on to the Hitchhiker’s Guide trilogy, whence the line originated. However, since she’s the only woman I’ve ever been with, I don’t have a large enough sample size to determine whether or not she’s right. 
M. Pete Marston, the son of Wonder Woman creator Dr. William Moulton Marston, e-mailed me to compliment me on The Wonder Woman Pages because of the academic work I did on his father.
From the rector of the church I attended growing up:
“Knowing both of your parents as I do, it’s amazing how well-adjusted you are.”
My unit was activated and sent over to Saudi Arabia during the Gulf War. One of the recurring duties was 12-hour shifts in foxholes guarding the unit from miles and miles of cold, empty desert. We were always paired up. Makes the time go by faster, and you could huddle for warmth (this worked best with male/female pairings). It was damned cold during those nights. Ice formed on the sandbags…but I digress.
One night I was paired up with one of the girls from the “popular” clique. One of the really pretty ones. Now, I was kindof a floating member between most of the subgroups in my unit, well-respected and liked all around (but mostly grounded in the “intelligent” clique). At that point in my life, I had not had much, if any, luck with the ladies. I wasn’t really shy, but was fairly introverted and had not come into my own.
Anyway, we spent the 12-hour shift talking and when it was over, she said “You know, [divemaster], you are a very interesting person and I really enjoyed talking with you. I never figured that about you. You should let more people see this side of you.”
That meant a lot to me, because we had really talked not just chatted the time away. Things that revealed our personalities more than the typical workplace banter. That was one of the first times I had real and tangible proof that my particular personality and what I had to offer as a person would someday connect with a member of the opposite sex.
A girl once told me I had restored her faith in men, which was nice, even though she lives 6000 miles away.
Also, a friend of mine suggested I should write a book on the sex lives of various animals. Which I’m pretty sure was intended as a compliment on my zoological knowledge.
I’ve had several people compliment me on my handwriting, especially my cursive. It’s funny. I changed my cursive writing after leafing through a history textbook and noticing how neat people in the 1700s wrote, that flowing style, you know? I try to model mine after that, but of course it looks nothing like it because of how cursive is taught today, 200 years later. Nevertheless, people seem to like my cursive.
The coolest compliment I recall is certainly provable, as it came from Bad News Baboon and was posted over on the DFW Dopers local interest board. She described me as “the Penn&Telleresque uncle that every kid wants”. The phrasing just tickles me, and I consider it a high compliment.
The second coolest would be provable if I could track down my professor or classmates for my college Shakespeare class. My professor was fond of having students read from the plays in class, and she eventually worked her way around to me (I had been studiously avoiding this). She normally assigned parts by pointing at a student whenever a new character spoke, thereby ensuring that everyone paid attention. She gave me the part of Richard III…then continued pointing at me for each additional part. Later she asked me (in a wistful sort of tone) why I was majoring in engineering rather than theater.
My nephew had to write a report on his favorite adult and he chose me. His mom (my sister) told me that he was really nervous about calling me on the phone and asking me some questions. He took about 5 days to think of the right questions so he wouldn’t sound stupid.
Another one: I got fired from my first-ever job. I deserved it. I was a complete jerk. Anyway, I soon got another job, this time as a dishwasher in a restaurant. I was trying not to make the same mistakes I made in the first job. About two weeks into the job, one of the grandmotherly-type women that worked in the restaurant told me that she “liked my style” after I finished doing something for someone. That one compliment was huge to me.
For some reason I can only think of compliments on my appearance right now. Must be having one of those days.
Someone (I don’t even remember who, sadly) once said that I look like Adrian Paul, who played on the Highlander TV show. I don’t see it at all, but it was a pretty cool compliment, since I think he’s pretty attractive.
An old friend and workmate of mine (who also shares my brithday) caught me off guard once. She was walking behind me, and out of the blue said said that I had “great calves” in a completely serious voice. Coming from her (an avid mountain bike-rider like myself), it was quite a compliment.
Short of finding these people and getting them to confirm what they said, I can’t confirm either one… but I still smile when I think of them.
Another friend sent me a letter after I moved away, and it had some great compliments… but I can confirm that one, so it’s out.
I once played in a band that opened for Ian Moore, When I went to set up my keyboard, I found that the power switch on my vintage prophet synth had gotten smashed in transit. I was unable to fix it on site, so I had to use the house piano…which kinda of threw me a bit because the sound guy didnt know how to mic it, and I thought the sound was horrible. After the gig, one the guys in Ian Moore’s band came up and complimented me on my playing style, said it was “tastefull”… I dont think anything I have ever done before or since has been called tastefull…
Teacher (after meeting my father): He’s yourrrrrrrrrrre dad? (if you think he’s intelligent, you’ve never been to Kentucky)
While I was dating my (ex) girlfriend, another girl I knew came up to me and asked me out in a bar. It was totally out of the blue, she said I was a “god” (we’d been out with a group of mutual friends and apparently I’d impressed) and would I do her the honour of “taking this next dance” with her. It blew me away b/c she was so upfront and out there like that (she didn’t even seem drunk taboot).
I introduced my current (at the time) g/f (not really as my g/f though - more as my date), her cheeks flushed red and she apologised. G/F then laughed it off and joked with her a bit before she left.
What was cool was that she (ex-GF that is) still went on about it for a week calling me “god” (try the name out some time, feels real swell), and to this day she remembers the girl who rushed up to me with the giggling crowd. Hell of a better achievement than my school grades.
I have a boyfriend who said breaking up with me was the dumbest thing he ever did.
And his mom told me she was sorry I wasn’t getting engaged to her son (when I announced my engagement). In a similar vein, one time my parents ran into the parents of a (different) ex-boyfriend’s parents. They remarked out of the blue to my mom that they’d always sort of thought that Craig and I would end up together (as in married), and it was too bad.
I call these unprovable because it would be sort of impolitic to get them to say it again.
I guess I’m a good girlfriend.
I was at a party, the next door neighbour was a somewhat snooty piano teacher, and someone had thought to invite her (I guess for political reasons).
I was playing my guitar, and as I started a particular piece I saw her nod to herself and heard her say “Ah, Bach”. I was playing one of my own compostions (which was a homage to Bach) and, if I was cooler, I would have just continued to play, but I was so gobsmacked I had to stop and tell her it was one of mine (I don’t think she could allow herself to enjoy it after that).
True, and completely unprovable.
Willard Scott called me beautiful when I struck up a conversation with him in D.C.'s Union Station. He also calls Al Roker beautiful, so I took it with a grain of salt.
I was told by Lenny Wilkens that I practiced basketball the way it was meant to be. No one around for that one, but coming from a 2 time Hall of Famer that meant a lot.