False reading on the L-test

[langel]

My wife recently underwent a psychological evaluation (MMPI) and tested extremely high (three standard deviations above mean) on the L-test.  This has me completely bewildered and I'm hoping someone can shed some light on possible causes. 

I'm particularly perplexed by the notion that high scores are indicative of deliberate and unsophisticated attempts on the part of the respondent to show oneself in a favorable light and the idea that better educated and sophisticated people tend to have lower L-test results.  I'm a member of Mensa, I have degree's in both math and physics, am a published author in a non-related field, poly-lingual.  I mention all of that only to qualify the following: my wife is the most intelligent, self-accepting and self-aware woman I have ever met. 

How is such a test result possible?  Could anyone suggest a possible cause?  Or perhaps another result which, when viewed together with an elevated L-test result, implies something different?

Thank you.