Eveillard's tax device

I just came across an interview with Jean-Marie Eveillard, who manages one of my 401(k) mutual funds—First Eagle Overseas. There is one little answer that immediately caused me to open the spreadsheets of each of my core holdings.

Fortune: You pay a lot of attention to companies' tax rates. Why? Particularly in the U.S., I don't like companies with very low tax rates, because it's a sign either that the Internal Revenue Service will catch up with them someday or that the profits they report are overstated. The average corporate tax rate is 35%. Any company that has a tax rate of 15% or 20% looks suspicious to me.

This suggests a simple device for estimating how much risk a company has because of trying to game the tax system. Companies with overly low tax rates are like ticking time-bombs. There aren't a lot of positive reasons for a company to pay low taxes. The device also warns of companies that exploit the US system that allows companies to use two sets of books. Oracle has the highest rating and it isn't exactly a blaring fire alarm.

Company        Tax     Device     
-------        ---     ------
Oracle         29.71%   5.29%
Canon          34.52%   0.48%
Select Comfort 37.78%  -2.78%
Berkshire      32.81%   2.19%
Sally          38.82%  -3.82% 
Marblehead     38.51%  -3.51%

Raytheon       31.79%   3.21%