I have frequently discovered tasks that I accidentally deleted. I think this happens by inadvertently swiping on a task on my phone, possibly in my pocket.
I think it would be really useful if OmniFocus had a Recycle Bin (Trash) folder (perspective) that works like with email - i.e. it holds all deleted items for a certain amount of time - say 2 weeks - before permanently deleting them. Anything that gets deleted would be stored there for that time before being automatically purged. This would only contain deleted items - not skipped/dropped/completed tasks. This would give us a way to recover them if we delete them accidentally.