Claymore, please consider adding rejects/incorrect shares per card stats to your miners. The recent addition of per card shares is nice but it would be really valuable to be able to spot the culprit card that causes bad shares without browsing through logs meticulously.
Press "s", see "Incorrect shares", it shows stats per GPU when at least of incorrect share is found. Also ETH shares are checked before sending to pool so miner cannot send incorrect share and "rejected" shares from pool are not related to GPU problems.
For general "rejected" shares stats per GPU for other coins - check my message:
https://bitcointalk.org/index.php?topic=1433925.msg19540815#msg19540815