As Ron states, the chalking on paint is usually due to 'something' (like moisture, mildew, and the like) attacking the paint and breaking it down at a QUICK rate. If the painted surface wasn't properly preped, then this could be the sign of both a bad paint job and/or a water/moisture problem.
The chalk and preferably the paint should be removed before it's repainted so AFTER the source of the water/moisture is corrected, you can do the job right. I 'hear' that using an oil-based primer/sealer is better. (I don't know for sure.)
Now, you can look around outside the house to see if you see signs of negative slope TOWARDS the house, or faulty gutters (during a rain storm), or non-extended downspouts to see if they leave water near the foundation. You can ask the owners what they know, and if you do, you may want to go as far as requesting a Property Disclosure/Disclaimer Statement from them too. The Realtor should know what they are. (IF they don't have them e-mail me or get someone else!) If you really like the property except for this item, then have the home inspected by an ASCI-approved Home Inspector. Talk to him/her about this problem. They are allowed to offer estimates on what it would cost to have the paint removed, walls preped and painted, and any other work BUT they're NOT permitted to offer to do the work. This would be a conflict-of-interest. The $300 (give or take) fee that they charge is not that much $$$ when it comes to mortgaging your life for 10-30 years!
My best to ya and hope this helps.
PS: Ask the inspector if you can have a discount on his NEXT inspection should you decide NOT to go with this house. Although, again from my perspective, paying $330 +/- is money well spent no matter how many times he/she does an inspection for you.