Calling a company to alert them about a deal/mistake/workaround.
Believing what an underpaid CSR tells you about pretty much anything.
Posting without searching to see if your question has already been discussed.
Having ethical conversations outside of the ethics thread.
Asking if the Annual fee and/or $200 airline spend count towards spend requirement on Amex Platinum.
Posting your own referral links and/or links to competing sites.
Posting the same questions 5 times (worded differently each time) and/or continuing to ask the same question after it was answered.
Posting that you're too lazy to read through a long thread, so you (just make the thread longer by) ask a question that's already answered many times in the thread.
Spending regularly on a debit card.
Posting a DD/DDF secret/trick/hack elsewhere and taking credit for it.