37-Release Steps to take

Here, in summary, are the steps you should take whenever you are buying a picture which has recognizable models in it from any type of photo agency:

Make sure the agency has model releases, on premises, for each and every one of their pictures. Make sure you can obtain a copy, if necessary.
Get a copy of their "Standard Model Release" and, if you have any questions or concerns at all, have it reviewed by an attorney. They don't use a "standard" model release? Be warned! And keep asking questions until you're satisfied that they know their business and are attending to it.
Assess your usage of the photo carefully: Is there any chance the model could deem your use "humiliating" or "libelous"? If so, contact the model to get a release for your specific usage-- or use a different photo.

Please do yourself a favor: If you are using a photo for commercial purposes (meaning for promotional or marketing purposes of any sort) make absolutely certain that the photographer or agency you're dealing with has a rock-solid system in place to be sure the model-releases are properly executed-- and available to you if necessary.

(Shameless self-promotion: At Comstock we have had strong, amicable relationships with models and modeling-agencies for decades. We didn't establish these good relations by playing fast and loose with either the models' rights or our clients' needs.)