The biggest disservice that troofers do is discredit by association the people who point out the real problem: that 9/11 has been exploited by the administration for all manner of malfeasance. The
Heimatsicherheitsdienst, the USA PATRIOT act, the invasion of Iraq, etc., etc., were all pushed through using 9/11 as a justification. Troofers undermine those serious issues by going a step off the deep end and suggesting that 9/11 was either carried out, or worse faked, by the federal government.
Indeed, the "9/11 Truth" movement does such an effective job distracting us from the real issues, I'm tempted to think that the entire movement was instigated by government provocateurs for that very purpose.
--Len.