I take it shorting is more of a "short term" strategy so a slowly declining stock is not the best choice? In case you can't tell, I've never done any short selling.
In the long run stocks tend to go up. The key word is tend. Yes, it is usually a time limited strategy altho mine seem to take years. I have been shorting Chang's for like 2 years now, waiting for the big dump.
One issue with shorting is if the company pays a dividend. Since you have borrowed the stock, you owe the dividend when it gets paid. Now you can sell short right after the ex-dividend date and close the position before the next one. But again, I think there are a lot more non-div paying ompanies that are worthy of shorting.
Shorting appeals to my sadistic nature. It is a contrarian approach. You look for stocks of companies that have appreciated enormously, way more than they are worth. You figure out where things are going to go bad, try to fix some sort of time frame for that, and then short. You need to ignore the chat boards and articles hyping the company. You want them to lose money, to lay off people, to suffer, to die die die. You fantasize about Enron, about seeing the CEO in the dock pleading for his life. You wish every bad thing on the company you can: gov't investigations, shareholder suits, liability suits, you name it.
It isn't for everyone.