In my opinion, for whatever it's worth, the only justification for selling something "AS IS" is when the lot contains more than 10 items - and that is also standard action terms worldwide - *OR* if an item is very badly damaged and that damage is obvious in the picture(s) and appropriately described and correctly identified. Otherwise, as Don points out, it is just a terrible practice.
It is particularly troubling when an item is misidentified, yet is sold "AS IS" for that way, the buyer does not even receive the correctly-identified item! Things like (for example) a 10c 1857 Type V (Scott #35) with the perfs cut off to make a fake imperf and then sold AS IS! Or coil stamps sold AS IS because if they are fake then they are NOT identified correctly as the raw material to make them is a cheap and virtually valueless different Scott number. For example, a Scott #356 coil fake is made from a perforated 10c stamp with the perfs trimmed off (usually a Scott #338) so when that fake is sold AS IS, the buyer is really getting a cheap #338 with perfs cut off! How fair is that? Yet such AS IS sales occur all the time on venues like
ebay and the other similar sites.
So one way to try to protect yourself from these AS IS sales is 1. Do not bid with any dealer who you see does it and 2. By buying from APS/ASDA members you get some added protection in that APS has a Bylaw which states that there is no time limit (for practical purposes) that a buyer is stuck with for returning for full refund any stamp that has been altered, repaired, faked or misidentified. Therefore, things like fake coils, or regummed stamps, or any stamp where the buyer did not receive a correctly ID stamp can be returned for a full refund. Sellers must abide by the society Bylaws. So very often the ethically-challenged dealers will not join APS or join but quit when they realize they can't get away with screwing buyers in these ways.
At one time,
ebay specifically prohibited AS IS sales, but recently I believe they abandoned that. So on one hand they fall over backwards to protect buyers with outlandish return policies yet look the other way when sellers foist off valueless material AS IS! Go figure!