How bad an idea is it to buy a shell and sit on it ?

[Matt F.]

I can't help but look at all these shells with some curiosity.  What's the downside of just tossing over some pocket change for one, and sitting on it for a while ?  Potentially seeing if you can get a couple in a row to do something architecturally interesting with, or just riding it out until the area starts to grow a bit and then finally fixing them up to rent or sell ?