You cannot get the best possible price for your house if it has problems that need fixing. Some problems are serious enough to scare off buyers. Some bring lower offers. Some should definitely be fixed. You need to balance repair costs against return on investment.

Must Fix Problems
In many jurisdictions–all of Canada for instance–sellers are legally required to reveal any issues that make a house uninhabitable, dangerous, or need costly repairs. Most buyers invest in a home inspection before making an offer.
Pay $200.00 – $300.00 for your own inspection before listing your house to find out what has to be fixed. Listen to the advice of a good realtor. Consider the costs involved and your potential return on investment.
Roofing Problems
Roof leaks or worn shingles mean no sale or reduced offers. The average cost of replacement shingles is about $12,000.00. Return on investment is usually over 90% and sales close quicker if the work is already completed when the house is listed for sale.
The $12,000.00 does not include repairing interior damage, replacing wet insulation, or removing mold in the attic.
Plumbing Problems
Some plumbing problems–like dripping taps or leaking toilet wax rings–are easy DIY fixes and should be fixed. They are obvious to inspectors and buyers. A potential buyer may wonder what other maintenance issues he/she will find. Repair any plumbing leaks that have damaged drywall, started rot, or mold growth. Hire a professional if necessary.
Mold Removal
Mold in the basement, mold in the crawl space, bathrooms, kitchen, or is sure to give a prospective buyer second thoughts. Even the musty earthy smell of mold makes people hesitant. Mold is a health concern for most people and deserves the bad reputation it has.
Electrical Problems
Too few outlets, no GFCI plugs in bathrooms, small inadequate panels,…