Hugh G. Rekshun said:
I don't see how it would really help them much, and as far as I know customers of escort agencies probably aren't doing anything that is illegal in Canada.
You're a material witness to a crime. They're not going to charge you.
They need proof that prostitution was taking place in order to get some of the big charges against the agency operators to stick (eg: procuring, living off the avails, etc.)
For example, the agency owners might simply deny that any prostitution was taking place, and your statement would help contradict that.
If it was incall you might want to be careful as in that case you were engaged in a crime too--though the cops are not really after you, if you hand them a case, maybe not smart.
By the way the AGENCY is committing a crime in Canada, even though the escort and the client are not (outcall). The agency can still be found to be procuring prostitutes, living off the avails, and so on.
On top of that they would want to know if you saw any evidence of maltreatment, abuse, etc., that would contribute to their charges of forcible confinement, uttering threats, intimidation, and so on.