One of my favorite examples of why short positions, by their existence, do not mean trouble for share price is LUN.  Pretty volatile share price however this volatility does not seem to transfer to corresponding volatility in short position size.  

There seems to be a perennial core short position with that stock that does not grow by more than a couple of million when the share price rises and does not shrink by more than a couple million when the share price falls.  

 

I think it could be argued that the existence of the short position may well be good for the stock.