One thing to keep in mind is that vertically polarized waves can
propagate by ground wave, while horizontally polarized waves can't.

Roy Lewallen, W7EL


True, but at close distances in which we have our man made noise sources, and
power lines contributing to conduct arcing, there is not that much of
"propagating" going on (almost near field). Our antennas "see" the noise
sources in their full "beauty" of "all kinds" polarization. Major factor is the
radiation pattern of the vertical (main lobe close to horizon) and its height
(lower to ground - "looking" straight at the noise sources).
Snooping with AM radio with ferite antenna can be very revealing in seeing the
polarization at particular point. Broadband noise source (spark transmitter)
can be very "ingenious" in producing and propagating the arcs over the wires
and air.

Back in Toronto I was plagued by 90% of the time with 20 over 9 from HV power
line noise. On 160 and 80 m, even from horizontals the "background" noise was
around S8. But having vertical whip stuck at the beach at Cape Hatteras, NC,
allowed me to hear rare DX at the opening and closing of the bands and getting
reports like "only or first NA station" with barefoot TX. Simply amazing. Oh,
and background noise is just non existent, S-meter needle sits at ZERO except
when static crashes.
One has to consider and select antenna systems based on requirements, geography
and noise situation. If local noise masks the signals, then fuggetabout it.
Some gadgets like noise cancellers can help in certain situations (single
source, phasing) also by positioning nulls in the antenna pattern at the noise
source can help, but it is royal pain in the butt especially for the contester.
I am willing to travel to no noise territory to enjoy hearing the band breathe.

So, saying that verticals are no good because they pick noise, is like saying
that Ferrari is no good to haul manure :-)

Yuri, K3BU, VE3BMV