If you didn't ASK to receive emails from them, it's spam and it should be reported as such.

Fuck unsubscribing from things I didn't subscribe to.

Not sure what you mean about legitimate businesses. I don't really trust any of them anymore. Those unsubscribe pages are still full of traps and they often don't keep you off new mailings that they can say you didn't explicitly unsubscribe from because this is a new newsletter that they thought you might be interested in. If I didn't opt-in, it's spam, and I'd like to think that maybe me labeling it as such might contribute to filters picking it up for someone else too.