...that they may not be disclosing fully. According to an article in today's Boston Globe, some researchers cross-referenced physician payment databases with journal article disclosures and found fewer than half of docs receiving $1 million or more from industry disclosed that fact. Though it does say that it's not clear if the docs didn't disclose or if the journals just didn't publish their disclosures, and the study was limited to 40 orthopedic surgeon researchers who made at least a million from one company, and two who got a million from just two companies.
Here's a link to the full article in the Archives of Internal Medicine. I'm not sure what you could, or should, do to ensure that is disclosing fully. I suppose an organization could hire someone to do background checks similar to what these researchers did, but what a hassle.