It depends on your personal ethics, if you are uncomfortable pursuing married women then I would say that its not a good idea to pursue them. Regardless its not a good idea to try and figure that out pre-approach, you should always approach and screen them out afterward. Have some sort of prepared line to use to see if she's married so that you won't waste too much time in set. I haven't tested this so its kj but you can playfully tease her with something like "For some reason I am getting "I have been married for over 5 years" vibes from you, are you married?" and then wait to see what she says.
Just one thing to keep in mind, its important to screen them out fast. When I was heavy day gaming I noticed that married women are the most receptive and compliant women ever, the first chick I went on an instant date was actually married. I'm not going to speculate as to why married women are like that but you should try to screen them out in the first 5 minutes because you might accidentally end up doing stuff with them and finding out too late.