What's your opinion on ghosting vs delivering hard truths?

Last night was a really unpleasant date. He's already asked me out again and I just want to ignore him and not think about it-- but is this an unfair thing to do? My friends all say to just not respond, and this would certainly be the easiest choice, but it also seems... a bit mean.

What do you think? If you were on the receiving side would you prefer to have someone say "I don't think I want to keep being friends with you because of X" or "I don't really want to go out with you again" or would you prefer radio silence?