If a publisher has ugly covers and/or generally "low" sales ranks on their titles then I tend to keep them off my list. But in truth I'm not even sure exactly what those sales rank numbers mean (yes, I know there's been endless discussion about this!).

For me "low" is anything higher than 1.5 million. I want to get in with publishers whose titles rank below a million.

How does this compare with what everybody else is doing? It seems reasonable to me but maybe there are factors I'm missing. Are there other sales rank lists I should be using?