Stained walls  and ceilings often happens when there is lots of cooking with oils and steam. When people Cook a lot of fish and boil a lot of soups this mixture of steam and oil and grease ends up on the ceilings and walls and they cannot be painted over without some preliminary prep work.

If a person is not experiencing have to be able to identify stained walls at that will probably bleed through it is best to prime the entire room wet stain blocking primer. There has been occasions where upon entering a clients Home where the client wanted to have their rooms painted with latex paint only to discover that there were smoke stains on the wall that were invisible. When an entire wall has been covered over with smoke stain it is hard to tell because the entire wall is the same shade of stain  cigarette smoke stain Is not a blotch stain but an over the entire wall or ceiling stain.
If you notice that your walls and ceilings seem to have stains on them like something brownish are yellowish, This is a good indication that this is a buildup of grease.
If you want to paint over this Area you need to first of all degrease the walls. Mississauga handy man painting usually uses TSP(tri-sodium phosphate) or some other type of degreasing agent sometimes even dish washing soap.
After the walls have been thoroughly cleaned, Rinsed and wiped dry you are ready to start stain blocking primer. Stain blocking primer Will stop stain bleed through. The reason you cleaned the walls so that the primer will stick the wall and not to the grease.

It usually takes about 4 to 6 hours for the primer to dry well enough to topcoat with finish coat. we usually use a product called kilz or SPS or bin stain block primers.

A light sanding will do to remove any dust bunnies and particles from the dried primer, Usually as paint dries it collects dust and particles from the roller deposit onto the wall. Mississauga handyman usually uses 120 grit sandpaper to remove the grit off the wall. Using a have your paper it might scratch the walls.

Now that your walls have been sanded you can apply two coats I've you're finish colored paint . And you will not have any bleedthrough of any stains now.