For me having open short positions in the instrument actually...

For me having open short positions in the instrument actually makes it a bit more 'predictable' (I use the term loosely, but I find signals have more meaning). Orders build around obvious places like swing highs/lows and equal highs/lows etc, and this potential liquidity becomes targeted. When key levels don't get taken out you can build a picture about the markets intent. Think of simple double top/bottom patterns for example. There is more meaning behind these when there are open short positions. The widely accepted nature of these patterns being tradeable are what attracts bigger fish as they can exploit them.