Do all short sale properties end up being sold in auctions?

not if there is a successful short sale

Most short sale owners pulled them off the short sale market. It was less than 30% getting sold and It may eventually be in auction and majority 90% are pulled off. So you are looking at 0.7 x .1 (%) =7% chance it will be sold through auctions and also on MLS concurrently. That probability sale number changes from location to location.

Short sale refers that the owner actually want to put it on the market not someone who is underwater.

Thank you !! 

My experience with short sales are slow (months, not days) and high drama. I just don't have the patience required for the process. Auctions on the other hand can be higher risk but the speed and certainty are nice. Given the current non-investor friendly SFH market, auctions are the only place I've found mediocre deals over the last 18 months or so.