I've coughed really loudly as we blew through 10,000ft at 320kts once.... they got the message, but no one said thank you.
Another time I watched a crew select speed mode for a climb without advancing the thrust levers in Class B airspace at 6,000ft... we started descending at 1,500fpm, and lost 500ft.
I've seen improper use of lights several times (no strobes, leaving beacon on, etc).
I've seen blown crossing restrictions.
And best of all... I've seen ALL of that on the same flight.