From my previous life as an auditor of several hotel properties (including Starwoods), I recalled properties not caring much at all about this - as they were happy with the room revenues and weren't so picky about the actual rates. After all,

a) the companies have offered such rates to groups on their own initiative; and

b) there's absolutely no way a leisure vs business trip can be differentiated by a hotel property, most especially in today's electronic age.

Hence, I personally don't think the properties really care and even if they did, it's one of those bizarre situations where a rule may be in place, with no way of enforcing it.

Similarly, I have never been asked to show CAA membership when on a CAA rate. I realize some have, but those examples are few. Pressure onfront desk staff isn't there to strictly enforce such eligibility rules. Just my 2 cents.