It's not just a case of looking better, either. A bamboo fly rod that has had care given to the varnish will last longer. There's a reason we put varnish on those rods & it's to protect the glue holding the rod splines together. If the varnish has cracks in it that will allow too much moisture through, the moisture will get to the glue & then you have some real trouble. The older rods glued up with hide glue are certainly in peril if the varnish is compromised. To keep the varnish in good shape, keep it clean & protected with a layer of good wax.
Let's take a look at how this simple exercise of cleaning & waxing can bring an old fly rod back to life:
Here is a photo of an older South Bend fly rod, made probably sometime in the late 1930's or 1940's. These rods were mass-produced & you can be sure that the varnish used on them was fine for the day, but certainly not of the quality that high-end rods were varnished with, even back then. Take a look at the varnish near the grip:
Now take a look at the same rod, but after the rod was cleaned & waxed:
The process to get rod varnish looking like this couldn't be easier: clean the rod with a gentle glass cleaner & soft cloth. Dry it down good after the cleaning is done. Use a cotton swab to get into those tight areas around the line guides, etc. Then apply a liberal coating of your favorite rod wax to the rod & buff off. That's it. It takes time, but the results are worth it.
So dig out that old, neglected rod from the back of the closet - the one you quit using because it looked so bad & give it a good clean & wax. If you see an older rod for sale somewhere, don't be afraid to buy it because the varnish looks a little faded. It just needs a good cleaning.
Clean your fly rod. You'll like how it looks so much better afterward & your rod will last longer because you took the time to show it some care.