in reply to
When do we change our replies?
I'd agree with the other people here who have said essentially, 'don't bitch that "we don't do C for loops"'. To me, the most perlish of all things is TIMTOWTDI. In the case of iterating an array, I would point out that it is more common to do it another, probably easier, way, but I wouldn't say that you should never do it C style (even if I don't).
Unbest practices of greater significance (such as bareword file handles) are important to point out, along with an explanation of the issue. But if the "issue" is essentially a matter of style, then be clear about that. Don't use scare tactics, lol.