I think there are some things that are misunderstond here. I know it is all opinion but if we look at some of the things in the past, that will give us some answers to shooting some myths down.
Cinder vinegar only helps extend the life of the syrup. Doesnt do anything for the bees. And in reaility, it doesnt really extend the live of the syrup. It just maskes with the smell. You would need a lot of vinegar to increase the acidity in the syrup. It would be better to actually add bleach to the syrup which will help kill the spores in the gut.
The paper method as mentioned above.... this can work but you can just use dry granulated sugar. Sucks up the moistue better then paper plus adds some security from starvation.
Screened bottom boards were proven not to help with nosema.
Michael is right, feeding anything will flush the gut out.
I see a lot of time that beekeepers have a hard time understanding things like nosema. I think of it like if humans had this problem. What would we do? Remember what mom always said? Drink lots of water. Water flushes the system. Same concept with bees. Flush their gut with something!
But, like most things, at the end of the day all that matters is what makes you feel better!