2008 Honda Accord Long term fuel trim, is -6% OK?

Hello Everyone,

I’m helping a friend purchase a used car and during at test drive, I’ll plug in my OBD Scan tool and look at the live data during a test drive. We test drove a 2008 Honda Accord today with 50,000 miles and everything looked great mechanically and from the outside, but the long term fuel trim was stuck at -6% no mater what we did, according to my scanner. Is this normal? I noticed that the air filter was dirty, could this be the cause of a rich condition in the engine?

Some insight in this matter would be greatly appreciated.