User 1 asks question, gets lots of answers, never comes back, doesn't answer anything, he just wasted our time analyzing and answering his dumb questions. He does it again, and again...
User 2 asks to get helped out with some tedious work like programming, reverse engineering. We get the job done for free, then he also disappears or moves to something else without giving a f.
(...)
User 100 keeps spamming the forum with silly questions. "The board is is square, should I use a square base to mount it?" - No, use a hexagon

. We all know this user starting with F and ending in arington.
Sincerely, we could make a community blacklist. Not to be abused because he likes pinneapple pizza and I don't, only for legit causes and must be a repeating behavior.
So we simply add those time wasters to our ignore list and filter the junk.