If you already hate them asking no questions is fine - you already know you wouldn't accept the job if offered so you should just say that and ask how quick the interview can end (sometimes they have quotas to fill and since you already have blocked off the time it costs you almost nothing to stay and can be a polite way to help someone else thus doing a good deed).

If you are inclined to like them enough to accept a job you need to ask questions! You need to be sure your inclination is correct. The worst case is you accept a job and realize after a month it is a bad job - all your other leads have gone cold and unemployment won't like you quitting now (check your local rules for if you can collect and if so what, but beware that you may have to keep working while looking for a job which is hard)

Of course there are different situations. If you are signing a 1 month contract you sill are watching your other leads anyway in that month. (or they are paying you enough to take 3-6 months off looking for the next contract)