No I'm no coin expert, but shouldn't you have gloves or something on when holding these? Or does it not matter? Good learning experience for me here.
Theoretically yes but they aren't in mint stage so whichever are silver don't have that shiny superfice anymore that gets nasty easy. At the end of the photo making and coin counting i had my hands black since a lot of the coins are old and very nasty specialy the old ones.
Note that some even if old and well yes a lot in deteriored condition most have most of the details in pretty good shape, i noticed a lot of the coins get the "face" always polished by the touch of other coins.
Also, a lot of the coins were in pretty decent shape before they got to whoever im selling them for, they weren't properly handed for sure which added a significant amount of small scratches specialy on some coins which are pretty easily deteriored, good thing is that a decent amount is avaible of whichever coin came after 1900 with several dates around which will be very well priced.
On the other hand I have the luckyb.it silver and rose gold plated coins I won in their tournaments and man, as my first coins of say touch of silver/gold first went nasty when i touched it with the finger once, the second one after removing the holo the glue remained there which is very annoying since i spread it thru the coin, i dont know how to clean them without scratching, i tried with a bit of cotton but seen on time that its not enough and could make scratches, im thinking silk could be good but just guessing. They still however with just a bit of grease in their capsules.
Im learning too
. I also seen some incredibly old coins at ... one could say cheap price comparing to some of the btc "artworks" from around. Dating from as early as 30 A.D.