Maybe not the size, but also the age? Or even just the fact of shooting film at all?
I've been out shooting with my EOS 3, and I've had opposite reactions from people. Everything from, "wow, can you still buy film", "wow, you shoot film, that's so cool" (these two are thankfully more common), to, "dude, get a real camera" (at which point I whip out the mamiya 645af if i've got it handy).
Sad thing is, it also happens when I've got my 7D (still a current-model, and still a very good one at that), I've had derogatory comments from 5D3 owners (because yeah, I can afford a $3000 camera that costs $4000 in Australia. When it came out I did the sums on film costs and bought the 3 instead), along the lines of, "out of the way, amateur" (sometimes substitute 'amateur' for 'tourist', even in my home town).
Mostly, it's all good though, Street shooting my Bessa L with 21mm Skopar and Finder a few weeks ago in Melbourne, a random guy came up to me and said, "hey, that's a really cool camera you've got there, well done" and walked off, nothing else. Felt a bit strange, but good. (I still wonder if he didn't know what it was and thought it was a Digital Leica or something).