I hate to seem too biased and cynical, but in my experience, honest boat sales (persons?) are Very few and Very far between.
You know...I blame two people for that. The owners of the brokerages or dealers and the purchasers. We all need to do a better job of encouraging and rewarding honesty.
I compare this a bit to college coaches. We say we want them to build a rule abiding program where students get an education, but then they can do everything in that regard perfectly, then get fired for not making the tournament.
Owners of dealerships say they want honesty and ethical salesmen, but they do nothing to encourage it. Just like the basketball player who doesn't go to class but scores 20 points a game, the salesman who makes sales can get by with anything. As an owner you're responsible for it all.
Now, as the customer, what do we do? Would you ever go to the owner or manager and say, I want to deal with a different salesman and I must be assured the first one gets no part of the commission. Otherwise I'm going somewhere else. Or do you walk because you don't like the way things are done? With cars it's easy as there are many others in town selling the same. I once purchased a very expensive bedroom suite, like nothing I'd ever purchased, from a store in Atlanta because the one in North Carolina made promises they wouldn't keep and lied to me.
All I can say is get recommendations from people you trust and don't go in blindly. Find a respected broker. On a new boat it may only be available one place although I know someone would went to VA to buy a boat instead of from the Florida dealer. I did remove a specific brand from my consideration because there is no way I could trust the builder. We bought cars in Tampa instead of Fort Lauderdale because of the behavior and actions at the Fort Lauderdale dealerships. Interestingly enough within a year they had both lost the franchises for those brands. From what I heard the manufacturer did step up to the plate on how they wanted to be represented. However, these were low volume cars. I don't expect to see Chevrolet police their dealers.
If I was a boat sales person or a broker, I'd be terribly offended by the behavior of many of my peers. Now, there are some extremely honest and ethical brokers. I know more than one who left a larger brokerage over the lack of ethics there.
And next time you aren't comfortable with a sales person, then find another one.