Mounting bookshelfs flush with ceiling - can you?

Instead of the standard true ceiling speakers for the surround channels in a 5.1 system, has anyone ever tried just mounting a bookshelf speaker flush (totally recessed) with the ceiling via attic? One can always buy a white speaker grill to cover the area in the ceiling. I imagine that a bookshelf in the $250 range (used) will sound better than a true ceiling mount speaker in that range.

Ideas? or am I way off on this concept?
Mounting bookshelfs flush with ceiling - can you?
You can do anything you want,it's your stuff!!Sounds like a lot of trouble to me though.
if the in ceiling speaker has a crossover it was designed for in wall. a typical bookshelf will not so there is probably too much baffle step designed into the crossover for it to sound right.
crazy idea
Bad idea. Regular speakers are designed to point at the listening position. Mounting them flush with the ceiling will point them downward. They won't sound right.
I guess I'm going with the general concept that speakers, in general, sound better when they are in a real boxed enclosure - like a dedicated speaker box - as opposed to just being a ceiling speakers with no box enclosure. I definietly have room to try to fit a real speaker with cabinet. It will point downward, just like a true ceiling mount speaker - but maybe the depth and richness of sound will be better sith the speaker in a cabinet pointing down as opposed to a true ceiling speaker?
there are speakers out there designed for in wall that have enclosures behind them. again, baffle step in the crossover is the biggest issue i see.
bad idea ... try a pair of the Martin Logan ceiling speakers on closeout from audio Advisor ... send em back if you do not like them ... of course you will have some holes to patch though :)
Just get a Boom Box save your money!!