For me, what it boils down to is this: You have a right to spend your money where you choose; and a business/property owner has a right to set the rules, as to what is allowed in his place of business, and what isn't. You can argue until you're blue in the face that it isn't really smoke, it isn't harmful [so far unproven], it's not illegal, blah...blah...blah; but if the proprietor says "Yeah...well...I don't want you doing it in here", you can either stop or leave.