I noticed a spider on one of my orchids and decided to leave it there. If I was my wife, I would be looking for a HAMMER to deal with the spider ...but I'm not. This lead me to wonder...are spiders beneficial to orchids? I would be normally inclined to think so as they would prey on any smallish bugs that might live in the orchid, no? It looked like a common house spider, almost albino in colour. Thoughts?

I know I have a couple of spiders living amongst my Orchids. I looked "mine" up some years ago, I think they are Phiddipus audax, a cute little jumping spider. As long as they stay in the greenhouse, I ignore the occasional little fellow getting a sunbath on top of an Orchid in the middle of Winter. And so far they stay put.
I wonder if they would really make a dent into a happy bug population, but surely they eat one here and there.

Spiders are beneficial to orchids due to their predatory nature. I am sure that they would help tremendously with controlling mealybugs, mites, aphids, ants, and almost anything else that they might encounter.

That's basically the reason why I don't kick out a few resident spiders.

Ants, on the other hand...

Same here, and the spiders usually stay up in the corners, out of my way.