I think it is pretty fun when other people want photos with you despite the fact that they aren't in a matching cosplay or anything! I don't usually find it creepy but there are always exceptions.
When I wear my Lucas cosplay from Mother 3, since he is also in a Super Smash Brothers game I get a lot of people coming up all excited because they play as him in the game. Usually it is guys and at first I admit it did weird me out, but I learned to have fun with it. If I didn't feel completely comfortable I would just hand them a prop (since they were not breakable at all!) and do a silly fighting pose with them so they could be happy and it was just a normal photo for me.
I think it is flattering when people want to do that though!