They all have ulterior motives AltaRed. These professional analysts who continually pump stocks have serious conflicts of interest, in fact much more so than an independent firm that might be short selling a stock. The real blame should be directed at these analysts you see on TV, newspaper etc -- they are highly biased. And watching these people for years, I've seen that they constantly make ridiculously bullish statements.
In contrast, the independent firms that do short selling are being much more transparent and straightforward. They are saying: "we think this stock is worth much less, and we're shorting the stock". They don't have the same hidden conflicts of interest and hidden linkages (as underwriters etc) behind the scenes, as mainstream analysts do.
Frankly, people just don't like short sellers because everyone tends to be bullish biased in general, and don't like it when their investments decline. Short sellers often become scapegoats, and it's a lot easier to blame them, as opposed to the stream of ultra bullish analysts, shills and pumpers who talk up stocks for years and induce people to pay too much for them.