How many mistakes can you find in this teaser from the Yahoo! front page?
Traditionally, either…or can be used to join only two things. And those two things must be parallel elements. So this use of either…or is ugly for more than one reason. First, the writer tries to join three items. Then, the writer doesn’t make any attempt to see that they’re parallel.
One solution is to remove the either and recast the sentence so that the items are parallel:
This little pup is really lazy, is really tired, or just doesn’t like swimming.
This little pup is really lazy or tired, or just doesn’t like swimming.