A bit of portfolio checking can go a long way to preventing this sort of issue. Here are some tips (based around this specific case):
1. Do not accept tear sheets that are posted in portfolios at face value. Rather, use Google to check the authenticity of all named parties to the tear sheet - venue, location etc.
2. Check the quality of the work and also, paying particular attention to tear sheets again - note the quality of grammer and spelling on these. Where possible check with the apparent source.
3. Drill down into any corporate website advertised or link to, from their portfolio. Check the quality of that web site - is it a pro site or something cobbled together by some hack. Check that all links to supposed partner sites work, and that these partner sites are genuine (again Google is your friend).
4. Ensure that if you click on any of the links your virus checker does not block access to the page indicating that it is a site on record as having potentially dangerous embedded content.
You have got a decent virus checker haven't you???? If not get ESET NOD (no affiliation)
5. Look for pictures in the MB portfolio with model credits - and obtain references. If there are loads of images with no mention of who a model is then be wary.
6. Use the MB search button on the forums and see the type of interaction a particular individual has with their peers - it can tell you a lot.
Now remember, none of these things alone is an indicator of a problem. But when these sorts of issues begin to mount up, then ask yourself if there just might be a problem.
Above all - BE SAFE.