While surfing a thread about a potential job change in Reddit's /r/cscareerquestions (DISCLOSURE: I'm a mod), I read the following comment:
"There is no such thing as ruining a career by switching jobs too often"
At the time this was the most upvoted comment in the thread, which troubled me because it is rather poor advice. I've written about my appreciation for job hoppers in the past once or twice, but I would never suggest to a reader that unlimited job changes would have a positive impact on a career.
When evaluating candidates that appear to be job hoppers, there are at least a few things that need to be considered.
A pattern of job hopping combined with multiple periods of unemployment is a huge red flag unless there are verifiable explanations for the gaps. Resumes depicting a number of employers > number of years AND one or two periods of unemployment for a given time period will require some explanation, and sometimes the explanation is a confession.
The job hoppers that have the most success are those that tended to finish a job and move along. The developer who built the system but didn't stick around to support it, the smokejumper that was hired into a difficult situation to accomplish a specific task, and the person who worked herself or himself out of a job are generally not faulted for frequent moves.
Some job hopper resumes show regular increases in responsibility or employer reputation, while others may be reminiscent of a downward career spiral. A series of job changes that reflect upward career mobility isn't indicative of a problem child, but rather a rising star that perhaps hasn't found the appropriate level of challenge.
Comfortable in Their Own Skin
You should be able to spot a job hopper that might become a questionable hire by listening to them describe the motivations behind their moves. There should be a level of both transparency and confidence in their explanations, and they may even admit situations where they made a wrong move. Candidates who fess to being blinded by an employer who made empty promises in interviews or presented an offer one could not refuse should gain some credibility points. Whether they are excellent employees or not, all job hoppers should have some expectation that they will be asked about their moves, and those most reluctant to discuss their history are likely the ones requiring deeper investigation.