If a record has cue burn it has to be mentioned, as does styrene noise, which is common - even on mint records you can get styrene noise. I try and play everything, sometimes maybe if it's a big list with a lot of 10 quid records on then some may slip through but I play about 98%. If a record has cue burn I just comment on the burn - for instance, if it starts before the track begins and ends on the first note, I'll still grade it as EX but mention the burn. If it's a significant burn, say 2 seconds or more, I'd probably downgrade it as well as explaining it. The bottom line is, I try to think how I would feel if someone sent me a record and hadn't described a problem - I wouldn't be happy, so I try not to let that situation occur.