I don't know, when I first visited Paris while still in school I somehow didn't find a single one of those, and lived a few days off of ham baguettes, spring rolls from Asian takeaways and McDonald's - everything going for "normal food" was very, very expensive.
Yes, this was a few years before mobile internet, and maybe it works if you live there not straight in the city center where the tourist attractions are ;) When I visited again last year I had no problem to find affordable food, but of course my viewpoint probably changed a bit.