On site like Date Check or Preferred 411, if a provider accepts and is listed, does that mean she is legit?  Do those sites verify that the provider's pictures are real?  Seems that if I am paying for a subscription it should go both ways?

P411 has photo verification. But the provider has to pay for it.  I use it and I sent in a candid pic of myself to prove that is is really me in my website photos.

Datecheck doesn't have photo verification that I know of.  I wish they did because I would also use it.  

Unfortunately it only means that somebody referred the lady onto the site the same as it would mean that a lady referred a gentleman onto either site.  P411 does hold ladies accountable for professional behavior the same as the gentleman.  

I've had a bad experience with a datecheck gentleman so nothing is foolproof.  But if you combine a good review history with either or both verification sites, you are tipping the odds in your favor.  

Both sites are very good if you travel, you would never have to depend on BP unless the area is just totally barren.

But I believe there's no 100% magic bullet to verify (or guarantee) if someone's legit... you've got to put the picture together yourself, based on verification sites, reviews, your email or phone call interactions with her, etc. The more pieces of the puzzle that you can find, it seems like your odds of securing the 'real deal' get better, but there's never such a thing as a sure thing. Or at least, that's my impression.

That said, I think P411 helped me establish my identity with a well-reviewed provider that I'd identified through searching TER, so to me it was worth it.

Check for reviews here or other review sites. While the providers are verified as providers, the pictures can still be old, and I have seen ladies on P411 who have shitty reviews here.

Date-check still has profiles up from ladies who retired. P411 will inactivate a provider's account if she does not check in every so often, so I think p411 is a little more trustworthy in terms of up to date legit provider profiles. With either site your odds of finding a legit gal is much higher than someplace like BP, but you still should do some additional research.

P411 tells you when the lady last checked in. If she has not checked in for months then you might not want to contact her via p411.

P411 requires that you use their messaging system to contact a lady for either a date or a prescreening.

They also inactivate a ladies profile if she does not log in for 30 days.
If you contact a lady for a date and she does not reply for 48 hours, she could have her account inactivated by P411 if you make them aware of the situation.  

Just recently P411 has instituted a new rule that any agency or booker must pay $20 per month for each ladies profile they manage on P411 due to the fact that agencies like to leave up inactive profiles to make it look like they have an endless supply of hotties when they really don't.

Objectively, these sites are more for the provider's benefit of screening than for yours. It benefits you to use these sites because 1) You're only giving your info out once to a third party, and 2) she is more likely to see you if you have been screened by known verification sites.

That being said, if she is also listed on these sites, she is *more likely* to be legit, but it is by no means a reverse screening tool for clients.