The 3rd coin on the top row in one of my pictures is one that has formerly had an acid treatment directly on the date. As you can see, it leaves an ugly splotch that only gets worse with time. Using vinegar will eat away at the entire surface, which leads to a more uniform look. I prefer this look because although it's obviously been treated, it doesn't look THAT obvious as the splotchy dates do. But that's just the way I prefer it. As far as value goes, it's all pretty much gone so either way you're not losing out...
Well folks I managed to get a 1913-D TII as well as a 1914-D! There ain't no better way to get those key dates for $0.25 or less!
Just found another undated buffalo in a roll. I've already got AC vinegar, gotta grab hydrogen peroxide next time I'm out
good luck! I actually just completed my Buffalo nickel set (sans 3 legs, 8/7, and the other expensive ones). 90% of those are acid dated
Join the club. I'd still rather be a member of this club than the alternative. Maybe one day we'll do shots of Geritol and prune juice together.