It's important to tackle the highest-priority problems first. There's no point in worrying about the lack of whitespace around operators if the program doesn't work: the bugs need to be fixed first.
In particular, if the whole design of the program is wrong — for example, if it uses an algorithm with poor performance — then it's the design that should be discussed in the review. It's a waste of time to review code that is going to have to be completely rewritten.
A couple of examples:
- This question from today uses an \$ Ω(n!) \$ algorithm. Until that's fixed, it's not worth worrying about the use of global variables.
- This question tries to do code transformation at the token level without parsing. This is never going to work and so it's not worth commenting on the code.