Most v6 issues tend to be accessibility in engine bay.
The most hated were the ones in transverse applications where the back head was crammed up against the firewall, making just a spark plug change impossible.
As far as just bad v6s..
Ford sold some hodge podge European market sourced 2.8 v6 in the Ranger for one year in the 80s due to an engine shortage.
I know somebody that had one - it was weak, thirsty, and unreliable. A carb'd 302 swap would have improved the fuel economy. Seriously.