Cheap coinz!!!1 
When I'm researching a coin, I'll go through the ANN thread and if I see the comments "Cheap Coinz!!!", "Chomp, Chomp, Chomp!", or anything like that, it raises a red flag in my mind and I will rarely invest in that coin. Definately a danger sign.
I think there are bargains out there, but they are few and far between. Look for coins with active/innovative development, strong communities, and ridiculously low prices. Diversify across a few of those then work to better the currencies you support.