Edit: Yes I did say that I was probably gonna pass because of the suspension issue, but also said i still wanted to check the rest of it out, which I did.(This is a form of bargaining, for if I found that the rest of the truck in good condition, I would either get you to fix the issue or knock the price down to compensate for the required repair, seeing that at the time all that was offered was a referral to somewhere else to fix it).
As for a cold engine, it sat idle for around 5 minutes beforehand as I checked the engine, heat, A/C and the electronics. And if you consider 4k rpm(again nowhere near the redline) "screaming", it was a 4L V6, its gonna make some noise but nothing that should damage it if it was in good condition.
So for future, you may want to lay off the exaggerations, and try to remedy the situation with dissatisfied customers instead of arguing with them online. It just good salesmanship.
Bit of a story but tldr: They are afraid of their products breaking when someone does even the slightest of tests on them.
Was looking at a truck and after looking at the carfax and repairs the salesmen turned on the truck(after having to jump a dead battery) and let me be while I looked over the truck and test it a bit. First thing i did was warm up the engine and see if any unwanted noises popped up by slowly increasing the revs by 500 every 10ish seconds in neutral then back down(was planning on going just over 5k as the redline was 6250, and while it was around 12 years old any engine that is worth selling should be able to handle that no problem). When I was just below 4k a guy(not the salesman) comes jogging out of the dealership heading straight towards me. The salesman, who went to help someone else while i did my inspection and testing, intercepted him, probably to let him know he let me look at it and was helping me, then just after I went over 4k the salesman came towards me yelling and waving at me to stop or the engine will blow up. I took my foot off the gas and I asked him why I cant rev it that "high" and he reiterated that that the engine will blow up if i let it rev that high for as long as I had(was around 80-90 seconds from when I started revving from idle at this point). I then told the guy that if they cant stand behind their products then I won't be purchasing from them. Before I finished that sentence he already started walking away from me at which point my language got a little more colourful.
As a side note, when looking underneath I noticed that the shackles for the suspension were close being rusted through and there was heavy rusting on the rear shock absorbers. When I asked about that all the sales said is he could recommend me to the place where they get their suspension systems fix as it would be cheap for me to do.
Needless to say won't be shopping or recommending them to anyone.