CPU mining is bad; they're not that well suited for hashing as GPUs, their cost is too much in comparison to their hashing speeds and you can't scale them (1 PC = 1 CPU, maybe 2).
using a gui miner i can use 4 cpu's and have had success mining many altcoins, we are on solar power here and I'm curious to know if the high power bills were the only reason people say cpu mining is dead? I've got my eye on a new desktop computer with octo-core processor for my next mining project.
You aren't going to mine a lot of anything on a CPU. There are coins out there ( I don't know CPU coins ) but even at free electricity you will need many computers to make a substantial profit. However, there are coins that you can buy that will 'stake', like RAIN, EMB, B3 and others that will generate more coins over time. It isn't technically CPU mining, but it can be profitable if you have enough coins to stake. The more coins you start out with the more coins you get.
Here is an example, XPTX has an interest rate of 230%. If you start out with 100 XPTX then (on average) one year later you would have generated an additional 230 XPTX, giving you a total of 330 XPTX.
I am not recommending the coins I mentioned. I am using them as examples, there are more coins out there, please research before investing in them and read up on staking.
EDIT: It's possible to stake while also mining a coin. It's not mutually exclusive, so you can experiment with both on same PC.