Lot of people tend to look silly, making faces and such as they compose the shot (whether shooting a cell phone or DSLR or anything inbetween.)
Now, there's two questions here IMHO. How silly do you look actually taking the photo, and how silly do you look when you are walking around in photographer mode?
I try to not look
too silly but I probably do. I generally get the straight-up shots by just looking up rather than lying on the floor, and I am not comfortable standing on benches or other things not meant to be stood on at Disney. I had a few times on this last trip where I was in the rear seat on a ride and I probably looked silly being turned around to shoot what was behind us instead of what was in front...
...and of course, there's the times where I'll have the camera seemingly pointed at nothing when using a fisheye lens, especially when using a tripod. There's nothing like setting up a tripod low to the ground looking almost straight up at one of the Tomorrowland palm trees to get odd looks.
Then there's the matter of looking silly because of the gear you're carrying. Mrs Groucho has pretty much shamed me into only wearing one lens pouch on my belt. I bought a pretty nice photo vest a couple years ago but have only worn it once or twice (and never at Disney) since I feel so silly with it! I also almost always wear my blue bucket hat at Disney, which can look a little silly; it's not the most stylish hat I own but it's great for keeping the sun off my head, for not being in the way during any shooting, and being easily crumpled into a pocket if need be. Plus it's a Subaru World Rally Team hat, which is a big deal to someone like me.
Fortunately, any embarrassment I feel about the way I look is easily mitigated by looking at some of the fashion atrocities people happily wear around WDW. I remember one woman this past trip, waiting in line for a ride wearing some outlandish pink "Juicy" outfit that looked like fuzzy pajamas. I didn't know what was most shocking - how hideously ugly it was, that someone would be seen in public wearing it, how great she probably thought that she looked, or how much she must have paid for it.
