This one just came back as an added "s", a few people who looked at it did not see the problem as obvious. Any idea what the process was in producing such a good fake apparently?
The placement of the S is decent-ish. Definitely believable at first glance, but that S is too big for a 1909. The S should be shorter. Also the edge of the lower serif isn't parallel with the edge of the upper serif. My VF30 example As for the process... I have no clue. Possibly removed from another cent, 1940s maybe, and glued on. I don't know really. But it does look like an S from a 1940s cent IMO.
As I recall, there are 4 mint mark placements. As noted, the closer you mimic one of these, the better at passing it off as legitimate. I've seen a number of fakes online that are truly convincing...most are pretty obvious. However, the safest bet is to buy a slabbed coin. Unless you are very experienced and knowledgeable about S VDBs (including the counterfeiting), throwing a bunch of money down may be an unwise gamble.
I got my money back; I spoke with a local dealer who said that the now deceased co-owner of the shop I got it at was a jeweler, and was known to palm off coins like 14-D cents and 16-D dimes with added mint marks on customers. Legal remedies for those ripping off customers like this is if they don't return the money in full, file a complaint with the state and hopefully the state will know what to do with proper evidence.
Looks like glue to me. Solder is too much trouble, and you would need to be a master with it to make it work.
Also there is usually a dot in the "s" from pictures I've seen. The vdb was off as well, which was strange, how is it that a P mint struck vdb and a San F struck one had different characteristics?