If your offer sounds good, the human will wonder what’s wrong with it?
It’s human nature to worry if an offer sounds good. Since you know they’re going to do that, make up a “downside”, and make this downside clear in your offer. Anyone reading your offer will find this vastly reassuring.
For example, if you rent cars for less than the best-known brand, you might say something like, “We’re only number two, so we try harder.” In this successful ad from the 50’s, Avis pointed out that they were not number one. It was a drawback, freely offered, a part of the headline. Readers of magazines stopped, and thought, and decided that they didn’t care about Avis’s drawback, being second. Readers concluded that the downside didn’t matter, and then went out and, greatly reassured that they knew the reason for the lower price, rented Avis’s cars by the thousands.
Knowing this important secret of the universe, go forth and prosper.