You are putting your life at risk, along with those you ride with !!
Although, no valve caps makes for quicker flat fixing, especially if you grind off the lawyer lips.

You should glue them to the rim opposite the valve stem to help balance the wheel.

Same here.

Presta valves already have a dust cap built in to them. You close the valve after you put air into it and no dust can get in.

+1

This.

I think they are pretty. I always get the brightest, prettiest ones. My current favorite is Green Apple.

Dust caps are the valve caps them selves. That little bolt that goes up and down and screws in to keep air inside is not a dust cap. There are 2 little cutouts on each side of that bolt that still expose the inside to the dust. PICTURE . Those little cutouts are used when you pump the tire so that the air gets in when the pump pushes the bolt down.

Basically everything is hollow and exposed to the point where that rubber grommet closes the valve. If dust gets where rubber and valve meet to close the valve, there is a fair chance the dust will get in between rubber and the metal, especially when you pump the tire and push the air inside.

Hence the name valve/dust cap.

I alternate between the dice and the eight ball. All the kids ask about them.

I can't speak for the usefulness of the caps, but I can for the nut thing. Once I lost the nut on a tube and just didn't worry about it, then a few months later when I got a flat, I took the tube out and there was a ton of oxidation and corrosion around the stem. And the other tube that had the nut in place had no corrosion at all.

I imagine that will eventually cause the tube to fail around the stem.

I wish my tubes lasted long enough to worry about this, but I live in goathead land.

I ridden and raced mtb's and road bikes for years. I have never had dust or anything else cause a problem with my valve / valve stems.

S valves are open to the elements and need a dust cap, I prefer the type with the built in valve tool.

P valves have no need for a dust cap as they are sealed against the elements but the nut is useful to keep the valve stem in place when the tyre is deflated or is being inflated. Using them is a matter of choice and in some cases, fashion.

If you remove the nut to save weight you should speak to a professional about your OCD.

The nut is there to rip the valve stem off the tube when you get a flat so you cheapskates can't patch your tube.

When I started training to race, my wife and I quickly ended up with such a professional. Low and behold, he raced bikes for many years, and fully understood the need to eliminate things that distracted from what mattered... things like nuts and caps. :-) Truth be told, I used the caps until recently. I buy threadless presta tubes so the pump goes on and off them easier - side benefit is no nuts to remove and throw away. There is enough to do keeping the bike working 'practically perfectly'. Who needs extra nuts and caps, especially if you pump the tires every ride, like you should, and lube the chain almost every ride, like you should.

The dice aren't as aero as the 8-Ball...

I'm so embarrassed. I'm taking my valve caps off right now. You'll have to give me some time to accept this before I get up the courage to take the nuts off though.

I use them, but note that I have upgraded to carbon caps to reduce the weight.

And by just what magical mechanism do you propose this nut stops corrosion?

I press the little valve tip down and the 110psi air blows the valve clean. If it was ever really muddy, I'd wash it with my water bottle.

I don't know, but the wheel without the nut had tons of corrosion and the wheel with the nut had none at all

im curious who goes long enough between tire pressure checks that dust collecting on the valve is a legit concern.

Zipp has been testing some miniature, dimpled golf ball-like caps that are said to add 0.027 mph at speeds over 32 mph.

This. I love these.

If they are not beneficial at all, then why did all presta tube manufacturers go through the trouble of machining threads into the valve stems for the caps and bother with even creating the caps? Obviously there is expense involved in that, so they must have to justify it. If is to only protect the valve until it is installed on a wheel, why couldn't they simply put a piece of tape/cardboard/plastic over the valve?

The most obvious justification is that enough people think they need the caps. Whether they really do or not is immaterial.

It's amazing what people will argue / disagree over. If you want to use valve caps then use them, if you don't then don't. It's pretty simple really.