"Well-reviewed" is in the eye of the beholder to some degree.  Several recent reviews by legitimate reviewers with a good reviewing history is what you should be looking for.  Some say ten or more reviews is a bare minimum but I'm not really quite as strict on my criteria.

Cityvibe is an ad site. Just like Eros anyone can place an ad and post a picture that may or may not be accurate. Finding reviews here on TER of a Cityvibe lady is the best way to go. Another issue with Cityvibe is that they often keep running a gal's ad even after she stops paying for it and is, in many cases, not even in the business anymore.  Be prepared for a lot of non-responses.  Still, I have found several great providers on CV over the years.

Having been in the hobby for a few years, I have developed a process.
I pretty much stick with independents. Since they are in biz for themselves, they have more interest in making a client satisfied so he can be a regular.
I only search for ratings of 9-10 in my area.
There can only be one review below this level - everyone has a bad day or the couple just don't click
RE: number of reviews - I have 6 as a minimum over no more than 6 months.
I have a 7-point criteria I look for. I read the reviews and really want 5 of the 7, but it is a big subjective based on the info in the review.

Yes I MAKE exceptions. I had a date with one provided that had only one review. She was hot, so I email the guy that wrote the one review. he confirmed that she was hot, hot, hot and more beautiful that her pix. i made the date,wrote a review and that started a flood of interest in her. She is one of my regulars.

it means 6-10 reviews minimum...  realizing that each unique coupling is...  well...  unique, still there should be a consistant good levels.  Since the topic is subjective, you need VIP to read the full reviews.   At least some of the reviewers should be experienced reviewers...   There should not be unexplained wide swings in the reviews...    

Before you get to deeply into the selection process, you should read the self-help section (by the life ring) completely and read back on this board until you can answer every question yourself.   It's all FREE!!  But no one can do this for you, nor see it through your eyes.