The matter depends for me both on what type of food it is and what condition the floor in the situation is.
If it's something like a fruit that hasn't yet been peeled and cleaned and you can do so, like an apple or orange or some such, then yeah I'd totally just wash and remove the outer layer and then eat the flesh. I feel the floor still needs to be fairly well-maintained though.
If it's something that doesn't have the benefit of an outer layer, then no, more often than not I'll tend to throw away whatever fell. The five second rule is a myth, so yeah, I'd rather not.