Well, to answer the initial question first, I "ghost" a lot more than post. In fact I spend an inordinate amount of time on this site.
As far as what motivates me to post, that comes in three variations
First is if I want to know(or think I do)the answer to a query and no one else has posted it yet. Along this line I'll sometimes come forth with a post that backs up another poster who I agree with.
Second is subjects that for whatever reason get me riled. A recent example is the "PETA placing Orange vests on deer" hoax that was in the "news" section. This fairy tale really pi$$es me off and I posted 2-3 times about it.
Third is posts like this one, asking for everyones input.
As far as the quality vs quanity thing, give me quality in any quanity. If I wanted to read quanity without quality I'd spend my time at Democratic Underground.com.
Don in Ohio