My worst experience was with a manager who was totally out of her depth, didn't understand developent or project management, completely abdicated all responsibility for risks and just updated gant charts all day. She would play the role of helpless female to get me to promise her the project wouldn't slip - so I wound up loosing sleep over things beyond my control.

Pretty much every conversation I ever had went something like this:

Mgr: Hi, hows it going with feature X

Me: Fine thanks.

Mgr: It will be ready on time won't it?

Me: Well we're on schedule so far

Mgr: But what if something goes wrong or changes?

Me: In that situation then we might be late

Mgr: But it's really urgent that we finish this on time (long pause)

Me: I can't see any reason why something would go wrong or change though

Mgr: Oh good, so you're sure we'll be finished by X then

Me: Well... yeah, I suppose

Mgr: Great

Then, if something did change or go wrong...

Me: We're not going to be ready by X

Mgr: But you promised! It's really urgent!!! (long pause)

Me: Perhaps we could solve this by reducing scope/using more people.

Mgr: Ok, you sort it out and let me know when it's all ok again

It took me a while to realise what was fundamentally wrong with this conversation.