Yes spiders do do all the things you mentioned, far as I know.
I think the case in point here though is esthetics. They're not
talking about a few neat, fuzzy cobwebs in a corner or two. In
fact, they're not even necessarily all spider webbings; some are
just spore growths from things that float in the air.
In the country especially the cobwebs will often cover the
entire north wall of a building, especially if there is
vegetation along it any higher than grass. Then it starts
collecting dust, insects, dead and/or eaten, pollen, spores,
anything light enough to float in the air.
Especially after a humid summer as we've had here lately, first
the side of the building begins to look a little dingy, then
gray, and then more black than anything else by the end of the
summer. My sister next door has one of the most text-book
examples of it I've ever seen this year. She tried sweeping and
that got rid of the fuzzies but not the black film. She tried
washing but that was a huge task, too huge for her. We've found
the pressure washer does the best job of cleaning and also has
enough force to remove the black from the vinyl without damaging
it since no soaps have been needed. Yet, anyway.
I normally wash down my siding a couple of times a summer and
it seems to suffice. No chemicals, soap or anything else
: > The Ortho Home Defender will keep them coming back for a few
: > If you don't treat the surface with something, they'll be
: I can understand wanting to clean out spiderwebs occasionally,
: especially if they're full of debris, but in general, they're a
: thing, right? Spiders eat flies, ants, mosquitoes, aphids,
: etc, and the vast majority are harmless. Why would you want to
: spiders away long-term?