I sold cars for four or five years or so and to turn this one on its head, a big pet peeve is the amount of people who you'd be completely honest with, and then they'd go and buy from someone who promised them the earth without any thought to how true it actually was.
Two key examples - someone who wanted a car on PCP that "won't be in negative equity". I explained that for the most part of a PCP that a car will be in negative equity and although some people may word things to claim otherwise, that's twisting the truth at best and an outright lie at worst. Spent two hours on an excellent deal for the customer, found the right car for them, a good test drive that lasted a long time - and then bought from someone who promised them that their car would "never be in negative equity". Guess what happened when they looked to see if they could upgrade to a bigger car a year in because they were expecting another child in the family.
The other one was when we had a brand new model of a car coming out. Again, like above gave them all the time in the world, no pressure or anything like that. Put together a really strong offer. Customer must have done it as soon as they got home but put it through Carwow and got offered a deal that when we sat down and looked at it, couldn't figure out how someone could offer the deal without losing a whole lot of money. Said that it looked very odd and to get clarification that it was the new model as opposed to the outgoing one, customer didn't do that, took the deal - only to find out two months down the line that it wasn't what they thought they were being offered and tried to order from me but within the same timescale that I'd offered when we'd first sat down two months prior. Went off the handle over the phone when the lead time had gotten as long as six to seven months, saying that I'd offered them delivery within three. Put simply - customer didn't get that model of car that they'd really wanted at all as they had to take something else to get a car within the timescale they needed.
I'm not going to pretend that I got everything right in my time - every salesperson will have a few horror stories of things that went wrong out of their control - or that everyone in the trade is brilliant, but there are more good salespeople in the trade than bad ones in my experience. Sales managers are a different story and are often the old Swiss Tony types who think that style still works and that everyone should follow their style and that's the big problem.
Still, there are some customers who absolutely will not listen to the truth and that either gives the salesperson two choices - not sell as many cars and have that sales manager breathing down your neck or take a "if you can't beat them join them" mentality.