There's no way for you to know except for what I tell you, unless you can independently verify through other means. Other means could be my participation in the boards on a variety of topics, asking those whom I've met previously, or asking me directly.
Her reviews, if consistent, can likely help allay your fears about working forcibly. Same goes for a general presence or activity on the boards over an extended period of time. Does she have a website with more than just the basics, can you get a sense of her reality? Asking her for ID is a double-edged sword with a sharp handle: you may get ushered out; she may refuse (what then?); she shows you and now you have to decide if it's a real ID or a fake one. Are you qualified to risk your liberty on that decision? Review can again help you here, and a website with more than the basics can illustrate her maturity level - granted it's not perfect, but it's a healthy start.So...I am not a regular hobbyist. I am a thrice in a lifetime guy, at most. My question is this--how do you know for sure that even well-reviewed providers are A. Truly independent (no one forcing them to be a provider) and B. They are of legal age. (or for me, 21, my own personal preference.)
I'm not here to judge but personally, I lose my interest in the hobby if I know I am contributing to someone in the biz under 21 and/or being forced to being an escort.
I'm aware there is likely no black and white answers but maybe someone can give tips to spotting something. Is it okay to ask a provider to see an ID with birthdate and her picture on it? (Her name could be covered up, I am not concerned about that....)
Hoping this does not turn into a debate as I am not here to start a fight, just want to have fun with a clear conscience. And everyone's conscience is different. 
A. There's no way of knowing for sure if she's entered the biz under duress, or what's going on in her personal life, but if you stick to well-reviewed providers with a substantial history on TER, you should feel comfortable that you're not contributing to her exploitation. Feel free to PM her reviewers to further allay your fears.
B. No, you cannot expect that she will show you her ID - she's not going to risk revealing her identity to a stranger. For the most part, women don't feel the inclination to lie about being younger until they are nearing 30, so unless you are worried about encountering an underage provider, you should expect that the early-mid 20 year olds are being honest. Or, you can simply visit ladies that are obviously past their early 20s.
Let us know if you're looking for a specific "type" and we can give you more specific advice for your search.
...Cancel before it auto renews. Read her profile and reviews. Look for a 25 to 35 yr old lady. Check the reputation of the agency if it's an agency lady. These steps won't guarantee anything but your chances are better.
There's no way for you to know except for what I tell you, unless you can independently verify through other means. Other means could be my participation in the boards on a variety of topics, asking those whom I've met previously, or asking me directly.
Her reviews, if consistent, can likely help allay your fears about working forcibly. Same goes for a general presence or activity on the boards over an extended period of time. Does she have a website with more than just the basics, can you get a sense of her reality?
Asking her for ID is a double-edged sword with a sharp handle: you may get ushered out; she may refuse (what then?); she shows you and now you have to decide if it's a real ID or a fake one. Are you qualified to risk your liberty on that decision? Review can again help you here, and a website with more than the basics can illustrate her maturity level - granted it's not perfect, but it's a healthy start.
My dick has threatened to wake me up every night if it doesn't get enough nooky
WOW
If she looks that young, have her pull out her DL and prove it or walk (er run) away.
Independent as opposed to Sex trafficking, that's what you are really saying right?
Without multiple visits and her getting comfortable, it's impossible to tell.
But, one pointer told to me long ago, (OK, a month ago) if the incall location is not a 4 star or better hotel or an nice appt complex, walk away.
Reasons:
A) Thugs are about to pounce on you, your gonna get robbed, beat up or killed.
B) It's Sex Trafficking
C) It's LE, well, it could still be LE in a 5 star hotel but it is less likely.
Yes, trafficking is what I was referring to...
Well, if you did not get the ad or a referral from a legitimate source or friend, stay away.
I have not run into this yet but if it is blatantly obvious that it is trafficking, again, rather hard to prove because it could just be a crack-head looking for the next fix, but...
Walk away, get on a phone, not your own of course and call the cops with an anonymous tip.
Its one thing for a lady to do this of her own free will, trafficking is a whole different thing.