To avoid the scatology, I'd start with the efficient market hypothesis, which isn't perfectly true, but is pretty close to being true.
It's hard to predict the stock market. If there is a lot of hating on a stock, the value is probably low to begin with, which means the stock has room to go up.
It is hard to predict, but many analysts claimed they have the edge and fool people making bad investments.
If I remember correctly, Jim Cramer's suggestion for how to use analyst recommendations is: don't buy a stock that is recommended by four or more analysts, and if you own it and a fourth analyst starts covering it, sell. It may not be going down, but its best days are behind it.