All my three ottos are still alive, no problems. I had seen them in the fish shop a couple of weeks before I bought them though, so I suppose if there were any losses, they would have occurred in the lfs before I bought them I'd seen them eating algae at the shop so I thought they'd be fine
The shop also taped up the corners of the fish bag. Apparantly ottos often wedge their heads into a corner of the bag on the way home. If the bags moving a lot, it can cover their gills and kill them. Try to get your shop to do that when you buy them. It might make a difference
Just flip the bag over... I always do that when I buy fish locally. That way there is no corners for them to get caught in. I also keep a pack of brown paper bags in my car to put them in so they don't get stressed on the way home.