The LW 5.3 beta prevents such files even being downloaded. Unlike LW 5.2

What makes you think they are not bad files. It might not be virus, could be any kind of security threat. Might also be commonly spammed files like audio files that are duds ... or with something to ruin the sound or song, or for videos, might be some kind of common porn.

BTW if you are really unhappy with LW 5, you could always downgrade to LW 4 if you wished; Downgrading to LimeWire 4 from 5 & resuming incomplete downloads