but fortunately EXTREMELY unlikely. There is no such thing as zero risk, but the scenario you desribed, while possible is very, very unlikely.

odds are quite low, but not absolute zero. Odds are much higher with an unknown.

Everything in life has risks. Take precautions to minimize the risk, but don't ever expect the hobby to be risk-free.

LE is, by and large, more interested in busting providers than in busting their customers. The time, effort and expense involved in setting up a sting with an established lady simply to bust a few of her clients is not really worth it.
Also keep in mind that LE goes after low hanging fruit. A well reviewed lady who operates discretely is really not what LE is interested in to begin with.

There are enough stupid, impatient and greedy providers posting on Craig's List every day in every major city to keep LE busy for quite a while. Nothing in the hobby is completely risk free but if you stick with the well reviewed and verifiable gals you will be OK.

But not likely.  If you have done your homework, and selected a well reviewed provider, your risk of being stung is minimal. Be more careful of ancilliary risks that could be far worse.  From personal experience, the greatest LE risk I have encountered (and this has happened several times) are DUI checkpoints on the way home.  For me at least, a DUI infraction would be much worse, and unless doing an overnight, will cap drinks during sessions at one...

... 'tis possible.  Highly unlikely.  As a newbie, you're smart to be thinking of worst-case scenarios, though.  Yes, it takes away some of the fun, but it could prepare you better and prevent you from making a critical error.  Keep reading up this site; you'll learn lots.