I just posted a reply to another thread about "Sitters" or "Ghosts"... there was some good advice there too...here what I posted...
Here's the link to the whole thread....
Those %#^* sitter outers
Hope it helps you take advantage of "Ghosts"...by the way..I find these sitters at every freeroll I've ever been in so I had to develop some sort of strategy eventually or go crazy and quit playing freerolls all together.. I'm glad I didn't, I've been slowly building up a nice bankroll from learning how to play them and last a long time...

...Good Luck !!!