Possibly the least helpful, but most humorous, way of leaving comments, is a large block of green text up at the top of a module.
There are all sorts of helpful insights buried in those comments to help me as a consultant understand my audience.
I agree with a lot of where Erik is going with his thoughts. The area where we probably have some daylight is that I’d rather limit comments to statements of why rather than what. Sure, when I’m pseudo-coding out a procedure, I’ll have a bunch of little “do this thing here” types of comments, but I remove those as I build out the code. Instead, explain why you’re doing something if it isn’t patently obvious, if you rewrote a query in a more complicated to read fashion because it performs much better, that kind of thing.
But in fairness, as long as your comments actually reflect the code, it’s really hard to say any code base is ever over-commented. It’s way easier to go the opposite direction.