This one should be pretty obvious, but most people don’t think about it. I see this a LOT. I’ve even done this one before. 🙂
Think about it: If you’re applying for a job and include an art test in your portfolio, that means you failed it! The result is that YOU look like a failure.
Avoid the appearance of failure! Look like a winner!
Secondly, realize that you’re not the first person that’s done that particular art test. You’re also not the first person to put it in your portfolio. That means that the company you’re applying at has probably seen this exact art test already, done by someone else, and possibly done better. So, not only does the person reviewing your portfolio see something you failed at, but he might also think “Man, that other guy did a better job.”
Ideally, your portfolio should be full of unique content that can’t be directly compared to other peoples’ work. That’s why that, although it’s tempting to model the coolest characters or enemies from every popular new movie or TV show, that’s what EVERYONE else will be doing, too. Be unique and set yourself apart.
Avoid comparisons! Be incomparable!
Finally, if you received proprietary materials for the test and you include that in the material you show in your portfolio, that’s very bad form. Even if you’re not under a non-disclosure, be respectful.