It's true in most cases but it really only helps with brown and white layers. White earlobes= white eggs (like leghorns) Red/dark earlobes= brown eggs(like rocks). It unfortunately does not apply to EE with any accuracy.
I don't know if it's true but I heard that the color of their ears is the color they will lay. Can't remember where I read that. Anyone heard that before?
Insanity is correct there is a link to earlobe color sort of but not to EE eggs, the reason for this myth about earlobes is the earlobe color link is not a natural link but an artificially selected for link, in other words someone got the bright idea to breed white earlobes on birds that lay white eggs, so it is not a true gentic link it is a selected for trait in some breeds but not all & many breeds that have white earlobes do not lay white eggs, and some red eared birds lay white eggs and not brown. So you can't really tell till they lay. Puddings in the proof as they say.