You didn't mention price or condition, so what I've got to say is pretty general. You'll want to check the condition of the pads and see how much side-to-side movement there is in the keys (like the RH pinkie keys.) Clarinet pads will usually be torn on the edges or on the surface if they are really bad, so that can be fairly easy to determine. You also need to evaluate the condition of the plating when determining value.
Play it with a tuner and see what kind of intonation you get. That's pretty much it unless you have any specific questions . . .
Play it with a tuner and see what kind of intonation you get. That's pretty much it unless you have any specific questions . . .