“Pointing out the faults” is the oldest trick in the book. As if the seller doesn’t know it? I would tell you the price reflects the condition and if you want to do that dance. I would ask you what it would go for in better condition?
If we are reasonably close, make me a fair realistic offer. You will probably get it with out the stupid “condition dance”.
If you don’t like the price, the ball is in your court. The only time I might even consider shooting myself in the foot, is if I can live without the book or it isn’t a high demand book. But of course every pulls this with the “good stuff” or “keys”. That stuff I am more than willing to wait on.