Any coin with a market cap under 10 million is a pump & dump. That said, you can make crazy returns on those coins if you are the first one in and first one out.
.... AND the world's biggest bitcoin exchange does not disappear overnight, like a thief in the dark, eh Peilthetraveler ? http://www.chicagotribune.com/business/sns-rt-us-mtgox-website-20140224,0,3242431.story