Using a term like as-is really is meaningless and basically is only saying the owner is not willing to make repairs, so don't expect any. You can still ask, they can still say no. All homes built are sold as-is and the only exception are ones to be built. There it is, you make an offer on it as it is, then you can ask to have this or that repaired and the owner can say no and you can walk away if your request is not agreed to, that is as long as that is all covered in the offer. Most offers give you an inspection period and most offers say that certain basic things will be working, like plumbing, electric, furnace, etc. This does not mean both sides can't agree to buy it with these not working, but they have to agree to it and if a lender is involved they may not allow it.
Listing a house as-is is not required since it is taken for granted.