Smartcash is one of the coins that is always not as profitable as one might think. There are quite a few people out there who like to rent nicehash keccak miners and they regularly hit the network with a gazillion of MH/s. And that greatly affects profits for regular miners. Happened to me a few times, I see the diff is at around 50 or less so I point my miners to it, hoping to get some coins for the next 24 hours, but then a couple hours later nicehash comes and the diff increases up to two-three times, sometimes even to 300. That goes for a few hours and then they disconnect. And the diff goes back down. The next day I check my 24h total, and I see that I've got a lot less than I was hoping for. The diff is still at ~ 50 though. So I keep mining but the same thing with nicehash happens the next day as well. It's a weird coin to mine, sometimes it does pay off, but with all those wandering nicehash dudes jumping out of nowhere it wasn't nearly as profitable lately as it used to be.