I have used quality belt dressings for many years. I suspect some that don't like dressings have been burned by the dissimilarity of dressings. Some are garbage, either lube or they actually break down the rubber. A good belt dressing helps it remain pliable and reduces dry rot and UV damage if the belt is exposed. They may improve grip which can make a belt a little noisier. Some of the things sold to quieten belts are just lubricants which makes the belts slip worse than ever, only quietly at least for a little while. This is a toothed belt running on toothed sprockets in an area never exposed to UV. Heat will probably do the most damage other than a basic design flaw.
The speed control rubs against the back of the belt if you turn the knob too far, can even bind hard enough to make the belt start burning. I removed as much of the metal that can rub against the belt as I thought advisable, modified the linkage so greater speed is created with a little more clearance, and verified at least ten thousandths running clearance where I arbitrarily decided was two-thousand RPM, max speed. I think I am pretty close to maximum speed, for the first time I can also run the lathe at minimum speed. The main thing is that I have a minimum and maximum speed setting and markings in between. I have a strong impression that I'm turning far less speed than indicated but haven't purchased a tach just to check something I can't change. I judge speed by vibration and what is coming off the cutting edge, seems OK for now.
I hope to sideline this lathe in the next six months or year so there shouldn't be any additional issues with belts in that time. If I do keep this lathe as my primary machine for very long I think I will be taking the entire Reeves drive sprocket system in to have it hard chromed to fight corrosion which is the primary issue. A little rust or trash gets into the sliding sheave halves on the drive and it is time for a disassembly.
This lathe isn't much but it has taught me a lot, a lot of what I don't want in a lathe too! No doubt some of the issues are my own doing though, the design and lack of strength in it's construction makes it unsuitable for blanks that seem like it should be able to handle them. The two horse motor and 15x38 swing and distance between centers seem to indicate much more lathe than this is. I did improve things considerably making a saw horse style stand to sit it on with a little ballast. The stand is screwed and glued, very solid and stable so far.
The picture was taken before the stand was complete but gives the general idea where I went with it.
Hu