The worst advice I've ever heard about technology in the classroom came out of my own mouth. It went something like "You should do/use/incorporate this because it is great and easy to do."
I don't remember what this was but I do remember the comment from one of my colleagues after I said it a couple of times during a professional development session. She stopped me at one point and asked if she could be perfectly honest with me.
Me: Of course.
Her: "Well, it is probably easy for you but it's not really easy for me."
Her: "Maybe. But until then, it's even more frustrating that I don't get it when you keep reminding me how easy it should be."
Me: I guess I'll hide this big red "That was easy" button until a later session.
I've tried to avoid the word in any presentation or PD session since.