Meh, I'd disagree with the absent-minded professor there. The deal really depends on the property and to an extent, you.
Some properties are going to off you more right off the bat; it just depends on what their unsold inventory is like and how badly they need the sales revenue. The higher the inventory, the more likely they are to cut you a better deal with incentives. In terms of the tour part, if you don't mind blowing anywhere from 30 minutes to two hours or so, and you have a cast-iron stomach backed by the ability to say "NO!" until you're blue in the face (unless you're really interested in buying, that is), you can probably escape in a decent amount of time with the base-level freebies / incentives. If you lack the willpower to say no to a hungry salesman or you don't want to lose the time in the parks, I'd say this isn't an option for you.
My own TS experience (full disclosure: I'm a TS owner) is that if you're interested in purchasing, hold out for the best deal you can. The first ex-Mr. Siren was one of those hardcases...he really, really put the poor TS sales guy through the ringer. Our base offer was a 4-day / 3-night vacation in Las Vegas. By the time we'd signed the final paperwork, we had the free Vegas stay, no closing costs, $150 in casino chips, tickets to the Rockettes (LOL), more free buffets than we could eat, taxi vouchers, two round-trip airline tickets anywhere in the continental U.S., and a 7-night stay in any Hilton hotel worldwide. When we left, the sales staff looked sort of dazed. It was funny, in a pathetic sort of way (I felt a little bad about taking them for so much, which is probably why he did all the talking).
Anyway, you have to decide what your time is worth and whether you can withstand the vigorous (read: pushy) sales pitch you'll be hit with. If the incentives aren't worth the pain of sitting through the final sales pitch, I'd say skip it.
EDIT: funny note on the Rockette tickets - the big-name guest star for their Vegas revue at the time was none other than Paige O'Hara, the voice of Belle from Beauty and the Beast. She was great!