I remove my glasses and adjust the diopter in the VF to compensate for my vision.

My glasses don’t get smudged and I use the viewfinder all the time. Must be the viewfinder material.

Here is your real answer:

Stick your eyebrow against the top of the viewfinder. HARD. This works with or without glasses. Honestly, I usually leave my glasses on because that gives me distant vision and the ability to scan for subjects.

So in general, stick your eyebrow against the viewfinder, and peer through the viewfinder through the top of your glasses. Takes a little practice, but you’ll get used to it with time.

I’m left handed. All cameras are pretty much right handed. I’m also left eye dominant. I had to get glasses recently and that played a big role in me retiring my old camera with the optical viewfinder. Using the LCD is much easier with glasses. Unfortunately, using the LCD is often impractical, especially outdoors, so I still use the EVF quite a lot.

I was getting my glasses dirty a lot from touching the back of my thumb knuckle to my right lens. It took awhile for me to realize that most folks look through the viewfinder with their right eye, so it’s likely not an issue for them. Unfortunately, training myself to use the right eye just seems like too much so I’ve resigned myself to getting my glasses dirty every time I use the viewfinder. 😕

A lot of the time, my glasses are just dirty.

I always have Zeiss wipes around for my camera lenses anyways. I am trying to develop the habit of cleaning my glasses more often. Those wipes work great but they are an environmental disaster.

I own an anglefinder with a built in diopter. It also has selectable 1x or 2x magnification.

You can also buy inline magnifiers with built in diopters. Some of them are selectable by just flipping them up out of the way.

Never had any issue with that on my Nikons. I use the viewfinder while using my glasses. I can use the diopter, but my mild astigmatism still makes things look a little fuzzy without the glasses on.

Set the diopter on the viewfinder so you can see without glasses?

Viewfinder cup should be removable. You can replace it with a different type of cup that doesn’t smudge your glasses.

I keep eyeglass cleaning wipes with me…

Use the diopter adjustment on the viewfinder.

Don’t know which body you have, but with my canons I can remove the rubber from the view finder.

Encountered same issue. However during shooting I did not recognize it really. Glasses are ‘dirty’ but I still could see OK.

However just recently bought contact lenses and it is a lot better.