($user, $fred, $hair, $thing) = split ...
The red flag is on code like:
($user1, $user2, $user3, $user4) = split ...
The "Red Flag" in both cases is not putting a numbered list of like items into an array. Putting a mix of different items into an array is very much a decision that needs to be made on a case by case basis. 99% of the time, the varX..varY case should be a list. It is a Red Flag that the person doesn't yet comprehend the array abstraction and is very much the same mistake as the hash abstraction error.
The example wasn't very clear thanks to you all abstracting "var" to mean "any word here" rather than the same word over and over with a numeral attached. (And yes, there are occasionally good reasons to do that but they are the 1%, not the 99.
Still, I don't see any need to point those Red Flags up. The people who don't get that far into Perl generally aren't going to read a Red Flags section of this site or any other site. :)
$you = new YOU;
honk() if $you->love(perl)