Legit Question: How do you know if a massage place DOES NOT offer happy endings?

So i have zero interest in getting a happy ending or anything like that, i just want a legit massage as im grtting very sore from muay thai.

last night I went to a massage place next door to where I'm staying, I read the reviews and all seemed good. there was literally a bit no sex sign on the window

I get in there and 30 mins the lady points to my dick and asks if I want to be finished, I was kind of blindsided and politely said no but it made the rest of the massage super awkward lol

is there any sure ways to know if a place isn't going to proposition you like that, any things to look out for etc.

PS. No I'm not gay, I'm married with kids. also nothing against anyone who wants one, it's just not my cup of tea (I was lucky enough my wife let me leave for 10 weeks to do muay thai, I'm not going to ruin my marraige over potentially getting caught doing something I can do myself lol)