Super common question. We take being approached as a compliment, but we take it no different that other people wanting to hang out and meet new people. With LS people, it simply means they may be looking for more fun that normal with you. However, there are some people with an agenda, and you figure that out quickly and move on from them. Make friends and be open to meeting new people. And a polite "no" always works...
Our thought is, LSers are everywhere and they mostly are extremely courteous. Like most said, without any sign on your behalf, you will get tested or asked but in a very subtle and respectful way, to probe if you are in the lifestyle or not. Just be honest! The people asking might be just testing because they're not in and are scared of the people who are. Some think it's a disease and are scared of being infected! 95% will take the "no we're not" and will keep partying with you because good people are good people. There's a saying that a third of the guests are standing on the "might fall over" fence! We found that for some of the open couples, these folks are the like cherries on a sundae... no agenda, no precast scenes. Just a spur of the moment thing that we were told is reliving a first time! First times aren't always the best, but ....¯\_(ツ)_/¯
My wife and I are not into the LS. We’ve only Been once but every single person we encountered as more respectful than your average jerk at a local bar. There was one dude in the hot tub who tried to be overly flirtatious with my Bride when I left the hot tub to get a drink refill; however, this group of people we had been drinking with came to her “rescue” and told him to gtfo essentially before I had even had a chance to get back.
One of the funniest moments ever at TTR for us was about this same topic. A group of us were still out well past when the music stopped and just having a drink and conversation by the pool. One of the ladies from a couple who were on their first visit to TTR was taking great care to explain how they had no problem with LS couples, but they were most definitely not of that group. A moment after, a woman named Lisa from the UK (from I think Lex and Lisa on CCC) calmly pulls the glass away from her lips and flatly says, 'Give it a day chickee". I can still see and here that with her accent. Hilarious!