If you're hiring some who you're going to need to mop the store, and during the interview you make it clear that they're going to need to mop the store, and you ask them if they will mop the store, and it turns out that they don't mop the store, that's considered a sufficient reason to get rid of them.

Having an explicit discussion on the topic of "Will you do this thing that we expect you to do?" means that (a) the interview tracks what actual day-to-day expectations are, and (b) if they don't do the thing, there's no need to feel awkward about wanting to not keep them around after promising something and failing to follow through on it.