that depends on whether you are his boss or one of the developers

if you're his boss, the answer is obvious: feedback, training, tracking, and - if necessary - discharge

if you one of the developers...good luck!

Beware of bad PM's with good reputations. Their primary skill appears to be appeasing high profile sponsors and spin doctoring bad results. This answer is directed to people who are developers on a project with such a PM. Hope it's not off topic if that's not the point of your question.

If you're a developer on a project with a PM like that, you have to take steps to cover your ass. If the project fails but somehow the PM manages to come out smelling like roses then more than likely some buggy software has been forced into production. When that software fails, some time after the project has been closed, the blame will fall squarely on the shoulders of the development team.

If the above describes you, you are in a difficult situation. You can't bad-mouth the PM, because you are most likely up against someone with superior ass-covering skills. What you have to do is to document scope changes religiously and re-estimate effort - unfortunately this will distract you from your primary job which is implementing the features that have already been included in scope. Request that all changes you are asked to make are properly documented and follow up with the PM to ensure that all stakeholders are aware of your changes in effort. Do not agree with statements like "that should be easy". Try to diplomatically protest comments like "a competent programmer should be able to complete that in no time".

Don't forget you are part of the team. Don't fall into the role of the outsider who complains about everything and refuses to step up to new challenges. Talk like a team player:

"just like everyone else on this project we are working hard to make it a success. right now we are deep into the current scope but we are dedicated to giving this new scope change the appropriate attention. Please give us time to assess it and we'll let you know how it affects our estimates... but also please be aware that the time to assess will cause delays in our current deliverable - we need to see that reflected in the schedule before we start."

I would say the essence of good project manager is that they provide valuable information to the client and the team so that both can do their jobs' well.

Not every project can be delivered on-time or on-budget. Sometimes there are factors outside of a pm's control. However, a good pm keeps everyone informed, tries to mitigate the risks, helps facilitate solutions and makes sure the client and team members are all on the same page.

It could be that there's a disconnect between your perception of what this pm is supposed to do and what they actually do.

The question is a little vague, but if the projects are continually late and/or over-budget I would imagine that he/she won't be a PM for long.

In the meantime, document EVERYTHING. Makes notes about when scope changes were given to you and your responses. Copy others (even co-workers, not necessarily superiors) on email responses to same. Send emails detailing concerns with scope changes, schedule changes, revised estimates, red flags, etc. Put everything in writing so there's a trail. You may not be able to prevent the project from failing, but you will be able to demonstrate that at least you were aware of the problems and were trying to do something about it.

As PJM said, it's a game of CYA. And it doesn't have to be complaining, it can all be done in a FYI manner. "I've looked a the changes and here's how I see them affecting us." Copy a superior or team member asking for corroboration or input. It shows that you're on top of things and initiating the conversation, it shows the PM that others are watching, and it protects you.

I am not a fan of the CYA mode. That is a sign and symptom of a dysfunctional, low performing team. The PM has the responsibility of developing a high performing team but the team member also has responsibilities here.

First, coming in on budget and schedule is not the only indicator of a good PM. Projects bust their budget and schedule all the time and can still be deemed successful. PMs that manage this, ie, have a strong EV capability that forewarns of bad variances, strong risk program that mitigates where possible, are in my eyes successful despite blowing their budget and schedule. Ultimately, if the customer is happy, the project is a success.

As a team member, what are you doing to support the PM besides covering your six? PMs have strengths and weaknesses; we all have this. Nobody is a master of all PM domains. If they say they are, they are lying or delusional. As a team member, if you have strengths where your PM is weak, are you jumping in to support the PM? Are you advising him of his threats and helping him keep out of rough waters? These are symptoms of a high performing team; no CYA necessary.

If you protect your boss, the boss will protect you, and the team and project will benefit.