This happens every year during race week. It's almost an official part of the festival at this stage. The cops publish a press release warning people about the influx of escorts in Galway and their threat to society, yadda yadda yadda.
To answer your question do they actually carry out the raids - yes they tend to publish details of at least one raid every year, usually, in my memory, at one particular prominent location in the heart of Galway.
My advice to any inexperienced johns - avoid popular escort locations for this one week. Next week everything will be back to normal.