One side is about to vacant and will need approximately $2000 for painting/wall repair and a good cleaning.

Not one of the guys that takes kickbacks from the agents to ignore the structural paint and say "it's fine, LOL" - somebody independent that you pay. 

In my case, after steam cleaning the carpets, and a fresh coat of paint, it was mostly gone after the painting and all gone some weeks later when I came back to check with new tenants in place.

Keep it simple and renovate them just how you would any other rental unit (paint, appliances, hard wood floors) basic things that you can get from Home Depot. 

The problem is that 50% of the walls in the house are covered with particle board (like the stuff in the pic, I found that on google; not from the house) and painted over with glossy paint. 

Using terms like "total rehab" or "cosmetic rehab" or "carpet and paint job" might be just as good as a tidy number. 

Even with minor paint touch up, perhaps a carpet that needs to be replaced, not all over the house, just in the high traffic areas, or maybe carpet is good but one of the bedroom doors needs to be replaced, you get the idea.

Property is a foreclosure and is currently vacant, but doesn't need much to get it rent ready, paint and a good cleaning(I was surprised). 

That is a bit tricky, because we sometimes have only 24 hours for paint and minor repairs, but it can be done.Of course it helps if your property shows well, is marketed and presented professionally and your rents are in line with the other 3 places your candidates are viewing that weekend.

Looking at a new roof new paint.