Before you can accept an offer from a potential buyer, you are required to provide the buyer with a Seller's Disclosure Report that discloses the full condition of the home, including any known problems or defects. This protects the buyer, but it also protects the seller against future claims for damages from the buyer.
If you're not sure about the condition of such things as the roof, the foundation, the wiring, etc. it's worth the money to get an inspection done - even though the buyer is probably having their own inspection done before you complete the Disclosure Report.
If you're selling your home "as is", the buyer's mortgage lender and/or insurer may still require you to make some repairs in order to remove any safety or fire hazards and to ensure that there are no code violations in the property.