Physician Salaries: What Do You Think about the Data?

What is the most reliable source for physician salary information? I've discussed this topic in the past, but I'd like to get some fresh input.

What do you think about these sources:

• Government sites like the Bureau of Labor Statistics (BLS)
• Executive search firms publishing salary survey data (do they elevate their numbers?)
• Public sites like the "Utah's Right to Know"
• Salary survey data from professional societies and associations

I guess the bottom line is: when do you think salary survey data is over-estimated, under-estimated, or correctly estimated? When it comes to evaluating self-reported data, I'm always a bit skeptical. Are you?