Answers

Please do yourself a favor and don't beleive "paint and primer in one". All that refers to is painted surfaces that have minor stains or a large color change. There is a reason that every paint store carries numerous primers. That being said, I echo the thoughts of the previous participants and say to use an oil primer that is specifically a stain blocker. These smell very bad but the smell will dissipate quickly and can usually be recoated in an hour.

I would echo what Steven says. Generally, flat paint is not washable. If you look at the cleaning instrctions, it will talk about being "scrubbable". This means you have to scrub a layer of paint off to get the dirt out. That is why the Magic Eraser works for a while. Ultimately, if you can simply use a degreaser and a rag, do it. If not get ready to paint with a "washable" flat or matte finish. Benjamin Moore also makes a very washable matte finish called Scuff-X.

Mr. Clean erasers work by using a very fine abrasive to remove either the offending dirt or the material that the dirt is in.  Think of them as a very fine grit sandpaper that is usually very gentle.  However, when used on paint, they will affect the finish causing it to spot on the wall.  The only way to repair this is to paint over it with the original color in the original finish.

Good afternoon,

The picture of the door looks to have polyurethane applied. If this is the case, that’s most likely an oil based finish. If you are trying to apply a latex base interior paint it will not work unless the finish is completely stripped off.

With out physically seeing this myself I can only speculate this to be the issue. The proper tradesmen to contact would be a Painter.

Thank you for inquiring with Ferris Home Improvements but unfortunatley this is not in our scope of work. Feel free to contact us with any questions or future projects. Have a great afternoon

I would have to agree with the Mr. Clean pads. The best way would be to paint over it only if you have the same flat paint...but I know sometimes it gets lost or dries out. So the eraser pad should do the job.

As others have said, Mr. Clean Magic Erasers work quite well without compromising the integrity of the wall finish.

Magic erasers by Mr. Clean tend to work really well without causing any paint discoloration. 

Mr. Clean Eraser Pad