[w003txz]

Hello, recently I bought a Pentax-a 50mm f2.8 macro from ebay. But the bad thing is I found some visible wears on the edges of the aperture blades, I believe they are oil. At present time, the aperture blades are snappy and function properly. So, if it is a big problem, do I need to return it? Thank you.

[MattGunn]

If the aperture is snappy then it is unlikelt that it is oil on the blades. When they are oily they get very slugish and sometimes stop moving completely, usually get stuck fully open. Aperture blades do sometimes show slight wear but this should not cause any problems.