This happens all the time. If the content you discovered would put your company at risk, or indicate that he is not a trustworthy individual, then yes, I would use it in considering whether or not I would hire him. If it is not something that should affect his job performance, or negatively impact the company, then I would be more likely to overlook it.

Even technical people get sucked into the fantasy that the web is anonymous. At the end of the day, is this a guy you want to work with, knowing what you do about him?

If he is a robot and does his job at work and nothing more - no, you should not.

Common solution could solve the problem

talk to him

P.s. That's just a guess - i don't know what's the content after all.

Let's first look at the first statement you made:

Before the second interview we googled him and found a MySpace page

And secondly:

The content was entirely personal and in no way related to his professional abilities or attitude

And then realise that MySpace has nothing to do with professionalism and has everything to do with you on a personal level.

However inappropriate, it doesn't necessarily reflect his professional conduct. Just because a man may swear in his home it doesn't reflect his abilities in the work environment.

Your candidates or employees non-work activities are irelevant unless they are criminal or demonstrate an ethical contradiction to your (employers) working principles.

This is a tough one, I'd say it's down to personal judgment. That is:

If his personal life is within decent bounds of society, then perhaps it should be left at that.

However if say you believe he's personal life goes beyond the normal socially acceptable, then you should be rightly concerned.

For example, if you think he may be engaging in illegal activities, or at least has the profile of a deranged lone axe murderer.

The only valid cases I could see are where the content could come to reflect poorly on your company, or if it implies that the prospective worker has personality problems that would damage worker moral. Otherwise, I don't think such things should be considered relevant.

You would have known the answer to this question the second you clapped eyes on the MySpace page.

It really depends on what the page says. If someone writes a blog entry saying Java sucks and then shows amazing Java skills at the interview then I doubt it's a problem. If someone is running a hate group online then you may have an issue.

Only you know the answer to this and it's not a programming-specific question either.

One question: how can you be sure that the page you found was actually him and not someone posing at him?

The first thing I do when the time comes to circulate my resume is to Google myself and see if anything out there paints me in a negative light, and do a little damage control/reputation management if it does. Unfortunately, I've discovered a pretty prominent sexual predator shares my first and last name, and they usually come up on the first page of the Google results. Fortunately for me, his picture is on almost every page about him so I'm usually in the clear if someone finds that, and I manage to get my personal website up to the top of the list with a few tweaks if necessary.

I'd say that most people should make the assumption that they need to clean up any of this stuff before the interview, so if any of this could potentially harm your company's reputation, you can consider it fair criteria for exclusion.

And rightly or wrongly, you might open yourself up to a discrimination lawsuit if the candidate ever finds out that's why they were passed over. Your employment decisions must be guided solely through any interviews, any skills tests you wish to deliver, and properly executed background checks (with signed and informed consent).

Welcome to the mine-field of human resources. :-)