[CQ-Contest] New tactic for finding a run frequency?

[Dale L Martin]

I always wonder and have never really found out:

If I find a spot where, with 500Hz filter in line, I don't hear a station on
the frequency, but I do know there are adjacent frequency stations above and
below but outside the filter passband, am I clear to 'take' the frequency?
(after the obligatory QRL? x 2, of course.) If I don't hear them in my
passband, will they also not hear me in their's?

73,
dale, kg5u