Credit Karma has always been very forthright with how they sustain the site. In plain language, and usually, before content, during, and random browsing. Of course it is another "we are the product, not the..blah tinfoil blah," but it is one of the best examples of the model working "best"
But people won't care, use them anyway, the bitch and moan.
Related/Unrelated, the best "identity protection service" I have used is
MyIdCare. Full disclosure, the first few years were free (thanks OPM), but the amount of information they monitor, and how quickly they get a notification
to you (vice your email inbox), is surprisingly fast.