I've never agreed with the angst towards 'reasonable' job hopping. We all recognize that interviews and research of a company can only take you so far in truly determining fit (on both sides) within an organization. There are also variables within the company that can change that are completely out of your control, such as leadership, company strategy, or team composition.

And there are also cases where a company promises a certain role or duty, the candidate joins, and then they aren't doing what they thought they'd be doing.