I'd push back on that first part. I think there are plenty of appropriate marketing tactics you could put under the growth hack umbrella.

To me, things are inappropriate when:

1. They're blatantly illegal 2. They cause damage or mental anguish to another (revenge, gossip, etc.)

Even with both of those though we're looking at some grayness, especially with measuring #2.

I do like the measuring stick of: would individuals be annoyed/disgusted/pissed enough to stop using.