Buying a used horn...
...is always going to be something of a crapshoot. Regardless of how careful the prior owner may have been, there are always fine tuning issues present. I have yet to purchase a soprano clarinet that did not have to be further adjusted to make it 100% prepared for my fingers and hands.
Corks are a basic integrity issue with a clarinet. If not intact and "live" (puffed up to the extent that they still provide an adequate seal), then you have been sold a bill of goods and have the choice of living with the issue or sending it back for a full refund. That said, getting a horn recorked is not an end of the world issue.
Pads are a bit more problematic. Sure, the seller may feel that the pads are adequate, but just as often (with a private sale) there are going to be defects. (A commercial dealer, in person or on line, will tend to repad a decent horn, just to be sure.) A full repad (which also implies an extensive overhaul, since new pads will need to be reseated and corks and adjustments need to be provided) is not a trifling expense, and one that (with a used horn) should either be provided if needed or clearly indicated if needed.
(An aside: there is no one less ethical than a seller who makes the claim that "I am not a musician, so I can't speak to the condition of this instrument, but..." in their ad. Generally, anyone that goes to the trouble of listing a musical instrument on eBay has a pretty good idea of what the horn is worth - the hundreds of listings for some sellers is evidence that they "know what they are doing". A honest appraisal in an ad goes a long way towards convincing me that the seller is legitimate.)
Personally, I'd rather not pay for the repad as part of the price of the horn, preferring instead to have it done to my specifications by someone whose work I know and trust. But, that's just me - I also have the keywork on all clarinets that have to touch my acidic fingers put through the silver plating process (as my hands eat nickel plate like it is candy), and have the ring heights dropped to account for my fat fingers. Your experience, like you yourself, will be unique.
Much the same could be said for the purchase of a new horn. Obviously, you don't expect moth-eaten (or mouse-eaten) pads on a new horn, and the horn is supposed to arrive from the factory in a "set up" condition. However, there will still be adjustment issues to suit the horn to your needs, and they should be provided by a retail seller. With the advent of the internet, this has changed, and the cost for such a "set up" would probably be borne by the purchaser. The price of progress...
Oh, and never (as in NEVER, NEVER) ever have all of the ooo|ooo finger position pads on a saxophone regulated so as to place them all the same height from the tone holes. The "typewriter" like level keyboard that this will provide may feel great under your fingers, but the horn's intonation will suffer as a result. Uneven and funky feeling is the rule with a saxophone.