[CQ-Contest] Zero Beating

[Mike Fatchett W0MU]

I noticed in the WPX CW test that a fair number of stations were way off my
xmit frequency.  This is the first time I recall making a mental note of
this occurring in a contest.  I had my skirts set at 300 and then 500.  Some
were off enough that I thought it was adjacent QRM till I tuned to them and
found they were calling me.

I understand the benefits of not being zero beat to differentiate yourself
from the pack.  Is this a case of poor operating, forgetting about your rit
or all of the above?

Anyone else notice this?