When I write my non-tie-in books (currently a Figure Skating mystery series for Berkley), I may base my characters' appearances on real-life people, but, if I do it right, nobody should know exactly who is based on whom.
However, when I wrote "Oakdale Confidential," the tie-in novel to the soap opera, "As The World Turns," all of my lead characters were pre-defined. And they were played by real-life people, whom I actually even knew and saw on a regular basis.
This caused a bit of a dilemma when I had to describe the characters (actors) in the book. Especially when I had to do it in the less than flattering terms that the story dictated.
One character accused another of being a "dandelion bit of fluff dumb blond." Another accused a grandmother of dressing like a tacky, wannabe teen-ager.
In a novel where the characters aren't (openly) based on real people, this wouldn't be much of a problem. In a tie-in, however, I worried: What if the actors thought this was me criticizing their appearance, instead of one character ragging on another?
Fortunately, no Daytime Emmy nominee ever called to complain, or threatened me in a dark and stormy studio.
But, as they say in Russian (my first language): It's not evening yet.