I have some poorly finished drywall that I would like to repair. I would like to install plaster veneer over the drywall, but this is normally not recommended. The following web page mentions an orange primer that can be used for this problem. http://www.bobvila.com/ArticleLibrary/Task/Building/Blueboard.html
Can you provide more information on this product ?
Your question is hard to answer without really knowing more. I mean what does "poorly" finished exactly mean. However, you shouldn't plaster it. If it's really that bad, I would cut out the bad section and replace it with new drywall.
The drywall joints are kinda rough. You can easily see the joints. With a lot of work, it could be fixed with joint compound. However I dislike drywall and would prefer the much harder and more durable surface of veneer plaster. In my experience, it is actually easier to smooth-out bad joints with plaster too. If I can simply apply a paint to the existing drywall and then plaster it, then that would be better than completely ripping out the drywall and replacing it with blue board/veneer plaster.