I was on a business trip to Key West once. I happened to have a free afternoon and did the tourist thing before settling in at Sloppy Joe's for a night I'd remember little of. A few hours and beers into said night, some random dude sits next to me at the bar. No big deal. We start idling chatting as I'm drunk and we are in proximity to each other. He starts buying me drinks. I think "cool, free beer". As the night progresses, he keeps buying drink and I keep remembering how I'm straight, married, and a firm believer that my ass is exit only. But, what they hey, free beer, and he owns some scooter shop in town, a discount may be handy in the morning, assuming I'm sober by then. Night goes on, free beer goes on. Eventually, I realize, I need to take a piss, and ditch this guy before he goes all "Deliverance" on me, so I do, and I go out the back door, while I assume he was thinking of entering my back door.

TLDR and the general point here is: "Don't be so uptight. Miillions of women get free drinks from straight guys without entertaining the notion of hooking up. May as well follow their lead when a gay guy buys you a drink." I feel no shame in getting free beers from a gay guy that had 0% chance of hooking up with me.