2 things might ease this kind of frustration:
1. a "withdraw application" button (suggested many times)
2. a lock icon next to level range that will "hard lock" levels and/or classes so that someone that doesn't meet the requirements can't even click on the LFM. (not suggested that I've seen, but probably has been suggested multiple times)
I've been running low level quests lately on BB streak I just toss an LFM with the appropriate quest selected at the appropriate difficulty (elite, of course) then put "elite for streak, ip". Since I'm generally in progress I just hit accept on all comers. I've not had anyone above the level range yet hit it so that I had to decline but I've had plenty of people that open with "share pls" or "what house" or "what quest"....and, of course, "is this p2p?"...I thought the "buy now" was fixed in that 3rd LFM column. This kind of thing does get a little annoying and I don't think I'm an "elitist" for being annoyed. I also don't always hit decline fast enough like, say, I'm in progress (as the LFM would have had said) and I'm near or past the end of the quest. I like to /tell then decline but I don't always manage to do that rapidly.