boots: yes
sneakers: yes
sandals: no
loafers: ?
clogs: ?
maryjanes: ?
Are we talking Best Dressed here, or what you want to go out in public with?
In public, I vote:
loafers, ok - bonus points for colored socks which coordinate with the shoes
clogs - sorry, I’ve never owned clogs; I have no effing idea.
mary janes - um, can be a cute look if you’re 8 yrs old or younger.
And: some sandals can look ok with socks. Not most, tho.
All of this is superceded if you are parading around in your own home. 
Socks for most things, but not jandals, rarely sandals (as I have no sartorial elegance whatsoever, I wore socks with sandals one summer, and ignored the comments), and not slip-on sneakers in the height of summer.
Boots, yes
Sneakers, probably (although I go out sometimes in something like sneakers without socks. But I’m just insane)
Sandels? If you wear socks with them you should have them torn off you and beaten to death with them.
Loafers, clogs? You probably shouldn’t wear them to begin with.
Maryjane’s? I’d go for stockings.
Boots: Of course
Sneakers: Absolutely
Sandals: ABSOLUTELY NOT
Loafers: With pants, sure if you’re more comfortable that way.* With skirts, absolutely not.
Clogs: Just say no to clogs. If you mean mules, no.
Mary Janes: See loafers.
*Applies to trouser socks, NOT athletic socks. Athletic socks are to be worn only with sneakers, or under boots where they’re not visible. Alternatively, trouser socks are NOT to be worn with sneakers under ANY circumstances. Yes, I’m talking to you. Cut that out.
What she said.
With one exception - clogs: socks ONLY if it’s cold out and ONLY when wearing pants. (particularly if you knit really cute cabled socks where the cable pattern travels all the way down the back of the heel to the sole of the foot so as to be shown off to maximum advantage in clogs/mules)
For me, it’s socks with everything but sandals.
If I’m wearing sandals, it means they’re coming off sometime in the near future, and I don’t want the hassle of having to keep up with socks too.
I wear clogs every day to work.
I wear socks and long pants with them.
I think that it is healthy and comfortable to be shoeless at work, but I can slip them on quickly to go to the coffee pot/bathroom/etc.
What’s with the hate for clogs? I firmly believe that if everyone wore clogs there would be no more war. I call it the clogs-for -peace theory. It’s really hard to chase someone when you’re worrying about your shoes falling off.
I have 6 pairs of clogs in my mud room, 7 if you count my house slippers. And I wear steel toed shoes all day at work.
Now Crocs on the other hand…
As for the poll:
Socks with everything except sandals and certain pairs of the clogs. I don’t do loafers, and men wearing MaryJanes just looks weird.
boots: yes
sneakers: yes
sandals: no!!
loafers: dress socks, never gym socks
clogs: no, but why are you wearing clogs?
maryjanes: tights because they don’t make hose for kids, and adults don’t wear mary-janes, do they?
This thread wins the “most perfect timing for me ever, ever, since the dawn of time” award for me.
Just before I logged on to my computer, like, 15 minutes ago, I was trying to figure out the answer to this exact question for these shoes. I bought them yesterday and am planning to wear them in about an hour and a half…
What say you? (I think no socks.)
I would probably avoid buying those shoes because the socks or not thing would confuse me. (although I like them - very cute!) Then I found the handy description on their site that lists them as a sandal. (? If you say so.) In which case no socks.
boots: yes
sneakers: yes, except while jogging when it’s really hot outside and you have those neato running shoes that allow lots of airflow through them, then no
sandals: no, no way, no how (and especially not black dress socks)
loafers: it depends, in the office yes, on Miami Vice no
clogs: yes, but you gotta have those crunchy, fuzzy winter hiking socks that you get at REI – or hand-knit wool ones
maryjanes: uh, no clue
Just say no.
I always gotta have socks on, unless I’m browsing the SDMB.
No socks with sandals unless it’s winter and I’m unable to wear shoes for whatever reason.
Boots: yes
Sneakers: yes
Sandals: I don’t do sandals. But no socks, ever.
Loafers: I don’t do loafers. But trouser socks.
Clogs: are the ugliest footwear on earth.
Mary Janes: if stilletto-heeled, nylons, or maybe bare feet. If low-heeled or flat, white socks.