I find the foot fetish to be pretty common. At least on here it seems to be a pretty common topic.
The chances of you getting her to go out with you are slim, but not impossible. If I where you I would work on getting the fetish under control. Yes there are probably women who really would like that, but I highly doubt they would want to reveal that to people in public.
The next girl you find you want to go out with go right ahead, but I wouldn't tell them about the fetish until you have dated them awhile. This way they have a better chance of understanding you rather than having them run off right away to the next guy.
There is also nothing wrong with you looking at their feet while at random places. Just keep it to a minimum if possiable and try to make it not too noticeable. As long as no one is getting hurt by your fetish there is nothing wrong with it.