The further down the name hierarchy you get, the stronger your names need to be to be sellable. Good keywords will have value in almost any extension, but the value change is exponential. The vanity TLD's like .cc and .ws could be a place to make money if you know what you're doing. If you can buy for $25 and sell for $200 and find them easily then there is profit in it. Just don't expect to buy for $25 and sell for $2500. I personally have a few, but I stick to are pretty strong ones like these, usually one or very strong two worders:
employees.cc
seats.cc
baptist.cc
instruments.cc
expired.cc
rockband.cc
dropship.cc
I'd rather have a super .cc than a nonsense three word .com with two hyphens. If you price them right, they will sell eventually.
I don't think LLL.cc domains have much value yet. Acronyms are mostly used by companies as short versions of their company name. Most companies don't really consider .cc as a viable option. However, I think these same companies might make a promotional site on a good .cc or even one of their products using the generic product name. If nothing else, they would park it on their .com just as a vanity alternative.