I encounter plenty of people like that. Some are friends and family, and some are strangers.
The latest ones that were fairly scary were multiple people posting how to navigate a roundabout on Facebook. They kept putting up a link that showed a roundabout and how to exit. Where I live there are probably 30 roundabouts within a 12 mile span north and south. Anyway, what they were posting and sharing contradicts the rules in our county here. They wrote tag lines implying everyone else was stupid. It’s scary! This is a driving situation they go through daily. I kept responding by linking the pamphlet that explains the rules and laws here, it has very nice diagrans, and asking the OP to take down their post. Plenty of people chimed in agreeing with me, so that’s good, and some of the posts were taken down. Taken down, but no one wrote me to say thank you, and they can’t believe all this time that they have been living here they were wrong.
Just today someone complained cars were not yielding to golf carts on the road. I linked the website that clearly states in bold letters that cars have the right of way here, and carts are to yield. Haven’t heard anything from that chick either. Crickets.
My SIL I no linger argue with, if I see a discussion is turning into a debate or argument I let her have her way. I let her be right. I either remove myself from the conversation or just nod in the affirmative, whether I really agree or not.
My husband in the last 5 years (I didn’t notice it before that) seems really sure about a lot of things that he has no reason to feel sure. He’s wrong a lot. WTH?! I really have no idea what is going on there. I’m baffled by it.
Just for the record, I think it’s better to put the price on the ad. I’m not sure if your husband’s best friend’s wife is wrong, it’s not necessarily a right or wrong situation, it’s just a difference of opinion.