I consider everything that is useless in a source as bad.

You see it and you think about it and then find out it shouldn't be there in the first place. This is waste of brain cycles!

Making blank lines a comment is useles, leave them empty if you want to have them.
Of course you will want to have them to make the code readable.

Putting a semicolon in front of a hash sign followed by nothing is even more useless (if that's possible).

Just my DM 0.02