Let’s say you’re eating lunch at an informal place such as a Chicago-style hot dog joint where transplanted northerners who miss the steamed poppyseed bun with Vienna beef franks topped with mustard, onions, glowing green relish, tomatoes, pickles, peppers, and celery salt.  An older gentleman comes over to your desk and, prior to asking permission, picks up the salt shaker and then proceeds to ask if he can use it.  Would you consider that rude, pre-emptive, presumptuous, or normal?

The person I was eating with was also taken aback and looked at the man and said “Say ‘Please’”.  This in turn threw the old man (who looked scarily like a modern day Kenny Stabler complete with southern accent) for a loop and he stammered and fumbled until he muttered “Please”.  This wasn’t a case of disrespecting your elders, as he was a lucid gentleman who simply should have waited until we said “Sure, go ahead” before physically taking the condiments. 

I’m sure my coworker wouldn’t have felt the need to make him say “Please” had he followed proper Asking Strangers For Stuff On Their Table etiquette.  I’ve been approached many a time asking for the ketchup on my table or some other item that another customer doesn’t have on their table.  It’s not really a big deal.  But I’ve never before have someone pick up the item in question before actually asking.  Flashing a Snake Oil Salesman smile doesn't allow you to presume what you're about to ask me is OK to do.