I misread a bug report right today and almost escalated the issue with the customer.

I shouldn't have dealt with the issue at all because I'm down with a cold and I know quite well that it reduces my mental capacity. But I saw the email and immediately thought: That's no bug. I covered exactly that case! And wrote back a small reply pointing to the change request specifying that. Shortly the project manager repeated the point - and quoted the spec. Full of self-righteousness I wrote a lengthy reply to the customer taking the report apart and quoting lots of spec (wrongly). The only thing the prevented a further escalation was that I realized that this was an instance of a pattern encountered earlier. Namely that even if I was right it might hurt my intermediary. So I decided to send the mail to him first. Luckily. Shortly I got a call, he wanted it explained and it became clear that the spec was right but the implementation indeed wrong - and my memory of the expected result clouded. The actual fix was easy. But the time collecting the reply and clarifying was still wasted.

Lessons: 1) Don't trust your mental capacity if ill. 2) Let hot mails cool or route them thru a supervisor.