ive been staying in the marriot/hilton hotels for the last 4-5 years and i usually have 6-7 people xPYou are aware that the hotel staff look at our forums every once in a while right?
what the hotel dont know, wont hurt them.
Not to mention that the original statement's a fallacy -- extra people not only cost the hotels extra, but can be a potential nightmare in a disaster situation. Not that anyone's expecting the Big One to hit during Fanime or some equivalent, but room guidelines exist for a reason. More people use up more utilities and supplies, generate more mess/waste, and mean more traffic in the hotel -- and if the hotel really wanted to and had cause, I believe they're within their rights to ascertain there are only the allowed number of people staying in a given room.
That said, it's pretty common knowledge that going over the room limit is hardly unusual when it comes to convention attendees -- if you're going to go over, just make sure everyone knows and is aware of what it implies (in terms of space, bedding, towels, etc.), and is okay with that.
The hotel will usually ask at check-in (or confirm, if you have it listed already -- I've changed my number within the max last minute because of circumstances and had no problem with it) how many people will be in the room. IIRC the rule of thumb is two in a single-bed room and four in a double-bed room ... and I think suites still fall under the four-person cap, but you could always ask the hotel to be certain.