When it comes to flipping houses most homes are finished in drywall. Drywall is very easy to work with, but at the same time it can break easily or become damaged easily.
Though if you know what your doing and how to repair minor damages to the drywall you can save yourself alot of money on your house flip. Its much less expensive to repair damaged drywall rather than attempt to replace entire sheets of it.
Here is a video I found that can help anyone and everyone repair minor damages done to drywall. This video shows how to repair minor to even major damages that can occur to drywall.