An owner should "disclose" everything that is "known" about the property. They are not required to disclose things they do not know. The burden of proving that he knew, without a doubt, is the problem , and I feel it's really not worth the frustration because you have recouse.
The reason for a "Home Inspection" and why we Realtors insist upon them, is so that these issues are uncovered (for sure) for the buyer, and there are no surprises. If you do not like the condition of the home after your inspection you can always ask for work to be done to correct the problems (repair pipes and eliminate pests) or you are free to cancel, based upon the inspection.