Exactly what I do...then if they keep at it I add that we've been there several times and don't need a "tour". After that they'll get one last emphatic "no thank you"...and then I'm done talking. That's when Jamie tells me I'm being rude. "Trust me", I say.
I agree with just saying no and walk away. This goes for any solicitation, stores or on the phone. Any reason you give won't matter. As long as they have your attention and you are responding, they will have something to say after your statement. Their goal is to break you down until you give in. If you are interested in anything they have to offer, holding out for better offers and negotiating will yield best results especially if you know you can get freebies.
We went to TTR for our first time in February. Having read a number of posts about the tour/timeshare issues, we were well prepared for it. We arrived around 8pm, and were asked if we were willing to meet with someone for breakfast the next day (and allowed us to pick the time). The forecast was cool and rainy the next day, and we planned on getting massages at the spa on our trip anyway, so when they offered to give us a big discount ($40 versus $280 for massage) we agreed. Having been to a number of resorts in the last couple of years, I've been through the process a few times. As first timers, I don't mind killing a couple of hours to get a tour of the resort, and a discount on something I plan on using (ie: massages). If you go on the tour (for the same reasons we did), then my recommendations would be to keep the small talk to a minimum. If you're willing to "sit and chat" with them for a long time, a 1-2 hour session can easily become a 3-4 hour session. They want you to chat and cozy up to them so you feel like you're dealing with "a friend" so you're more likely to buy. When you get to the sales room, don't ask a ton of questions, try to get them to get to the "bottom line" sooner rather than later. The sooner you get to the final sales pitch, the sooner you can say "no" and get on with your day. Apparently there's some new regulation in Mexico that they only have one crack at selling you. If you say no, they can't bother you or pursue you further than that. As a result, they need you to commit "on the spot". They won't give you a couple of days to think about it, talk it over, etc. If we hadn't already known in advance we were going to say "no", then that certainly would have convinced us. As someone else referenced, there's no way that I'd sign a contract in a foreign country without having it reviewed by a lawyer. All that said, we listened to what they said, and were polite but firm in saying "no thanks". In particular, my wife just kept saying "I'm sorry, but I'm just not comfortable making a big decision like this on the spot without time to think about it". They said "we aren't allowed to give you time to think about it, you have to decide now", to which we responded, "then its definitely a no". They seemed disappointed, but weren't dicks about it, or pushy, or anything like that. Meeting over, got our discount certificate for the massages, and on with our day. The whole experience lasted a little over 2 hours (including the time we were eating breakfast). So we sacrificed probably 90 minutes of a rainy day to get a tour of the hotel and discounted massages. If you're planning on getting massages anyway, and don't mind sacrificing an hour or so, its not a bad option. Oh - plus they're more than happy to serve you premium liquor while you're meeting with them. So as long as you're not the kind of person that lets a couple of drinks influence your decision making, you don't have to stop drinking while you sit through the meeting
We very sternly told them NO, we were not interested in anything they had to say, she followed behind us talking for about 25 feet, and eventually got the point and gave up...
We told them that it was our first time and that no matter what next year we have to take the kids to Disney. They understood and never bothered us the entire time we were there.