Once, when we were young gullible first-time home buyers, we got a call from someone who said he was from some sort of local "real estate agent board" (which may have existed but I'm sure he was the only board member...) who said that the "board" always conducted a survey on the "professionalism" of local real estate agents after a sale. Or some kind of gobbledy-gook like that.
He asked if he could stop by to ask us some questions. Having liked our agent and wanting to say something good about him, we agreed.
It didn't take any time before the subject got on storm windows (this being in the early 70's and in Michigan, that was a serious subject) and lo-and-behold, he also just happened to also work for a storm window company that was having a great sale on storm windows. Whatta coincidence!!! How much money it was going to save us on heating bills!!! It would pay for itself in no time at all!!! Before we knew it, we had fallen for the spiel and had signed up for new storm windows.
Luckily, Michigan had a "cool-off" period in which you could cancel a contract and we promptly cancelled the next day after we had slept on it. Our old storm windows, though definitely old and heavy, worked just fine for the rest of the time we owned the house.