The odds of someone filling your O2 tanks with air instead of O2 is
just as deadly and just as likley to happen as someone putting Drain-O
on your sandwitch instead of mustard at a Subway restraunt. Well, maybe
not as likley, but you get the idea. Some things in life you just have
to risk. Thats not to say fuel sumps need not be checked, or simple
inspections shouldn't be made, but there exists a line which seperates
reasonable precautions and insanity.