IMO most of all times the forkseal is dirty and with a business card you can clean the seal quite easily.
Take the dust seal down, and push the business card between the seal and the fork leg, go around there once or twice till clean oil drops out.
You could refill the forks but preferible is a complete oil change. I prefer atf, I change fork oil every 40 hours.
Get some seal safers mount those and forget about dirty seals.