The tax code has a choice. If you itemize, you had a choice of taking your state tax or sales tax, but not both.
The ad copy is offensive, like some of Motley Fool ads posted here, it has a remarkably low signal to noise. Given how many returns are filed each year and what fraction of those itemize, the potential deduction only applies to the limited few, perhaps 20% of filers, but of those, most are still best off just using their state income tax.
Not a scam, just someone using too many words to try to get you to subscribe to a newsletter or buy a book.
Edit - The IRS publishes a wonderful number of reports on Tax Stats. The most recent report covers 2015. 150M returns filed. Of those, 45M returns itemized their deductions. 30%, higher than the guess I made while answering above. Of those 45M, 9.6M used sales tax vs state income tax. 21% of itemizers, or 6.4% of total returns.
The specific issue "is it a scam" has an answer of "no". The US tax code is littered with odd choices that few are likely to be aware of. Very often, it's just a matter of searching and reading about what might apply to you, the individual/couple doing your taxes. This particular issue is worth a bit of money to those who happen to have a high cost purchase or series of purchases in a given year, putting their sales tax well about their state income tax. I would imagine that itemizers who live in a state with no income tax are aware of the sales tax deduction.