When you go to a time share presentation you will probably have been offered some kind of gift, discount or incentive to attend. Most time share companies give away bottles of wine, spa certificates, rounds of golf and the like or may provide free excursions, complimentary meals, day passes etc. These types of time share gifts are not taxable as most are considered a courtesy or comp. If you are told that you have to pay a tax on these at the airport, you are probably being scammed in some way.
Some time share developers may offer cash incentives and this can cause a little concern as in effect, the prize is an income of sorts. However, most reputable companies will offer discounts or monetary incentives that are redeemable against the purchase of something, so as to avoid any grey areas.