A: In almost every situation, you are required to report the income on your tax return. The salesperson was undoubtedly referring to the "vacation home" tax rules, which allow you to exclude the rental income if you rent the "home" out for less than 15 days in the year. However, that rule would treat your timeshare as a vacation home for the year only if you and friends and relatives personally use it for at least 15 days during the year in addition to the days it is rented.
If you don't meet both of the 15-day rules (and some other rules that are less likely to apply to timeshares), the income is taxable, just as other income you receive is. In order to have a chance at meeting the rules, an individual must own a minimum of three weeks at a single resort, with at least 15 days used for personal purposes.