It's the more ambiguous ones I see that get people to argue about how PEDMAS is interpreted. Your example is unambiguously -4. But consider:
6 / 2 (1 + 2) = ?
I approach the problem the same as I would 6 / 2(x + y). When the multiplication is missing 2(x + y) is a single term. The implicit multiplication is part of the parenthesis and reduces the problem to 6 / 6. People who argue that you have to strictly use PEDMAS left-to-right will divide 6 / 2 first and get 9.
Neither way is wrong as long as you can explain the process but everyone wants to argue and have there be a single answer.
I’ll stick my chin out, and claim that nobody who knows anything about math would ever write the expression like that. Either use parentheses or a long, horizontal division bar making it obvious what groups with what. As given, it looks like some small-minded school teacher (I’m not saying all teachers are small-minded, just a few of them!) who has taught a set of rules, with little regard for actual practice outside the classroom, and then tests to exactly those rules.
When calculating by hand, it’s useful to have multiplication × (not dot, if you value your sanity at all) binding as tight as division / and multiplication-by-juxtaposition binding tighter than that. On the other hand, this only comes handy when your intermediate results are so large that one or two levels of (unambiguous) fractions still aren’t enough, and if at all possible you shouldn’t be communicating results that unwieldy. If you really need to, don’t confuse your readers and use some bloody parens. (You’ll probably need more than one kind.)
I see it as more important to realize that not all questions are well formed enough to have a right solution.
A test question like "6 / 2 (1 + 2) = ?" is not asking for the mathematical meaning of those symbols it is asking for "Guess what I as thinking when I wrote this".
(Unless it is a programming class and you are learning how the compiler reads your code)
6 / 2 (1 + 2) = ?
I approach the problem the same as I would 6 / 2(x + y). When the multiplication is missing 2(x + y) is a single term. The implicit multiplication is part of the parenthesis and reduces the problem to 6 / 6. People who argue that you have to strictly use PEDMAS left-to-right will divide 6 / 2 first and get 9.
Neither way is wrong as long as you can explain the process but everyone wants to argue and have there be a single answer.