Both of my favs consider themselves to be UTR and both have a slightly different approach to getting business. One has no website and no TER presence, though she does read here she is un-reviewed and almost never posts anything. She sees new guys through referrals when she is looking for new business but that is rare.  

The second lady has a web site and will post an occasional ad on Eros or a local site (she is based in South Jersey).  She has no reviews, no TER presence at all and is not even a member.

I think you will find that the definition varies a bit from lady to lady.  I think you can post on any board and still be UTR.

For me UTR means exactly that: Under the Radar.  This is a lady who in both public and amongst most of the "hobbyist" community does not wish to be known as a provider.  This includes no reviews, no website, no listings, nothing.  She only sees a very small circle of "friends" and even discourages expanding it even further - unless that "new" person is lucky.

This, imho, is UTR.