Most folk prefer un-marked bars, especially bars with serial numbers. There's folk here who don't care about the cosmetics but others like to have their silver in perfect condition. You'll be able to sell the bar easily enough. Don't sell it below spot and if the bar is available for you to buy, I wouldn't hesitate if you consider it's a good price.
I'd pay about spot -- if I were forced to buy. Would gladly pay more for an unmarked one of those. Just me, though. I'd be a little more lenient had they tested the bottom or side, instead.
I mean, I personally had not heard about using acid on silver to test it. I have an older bar with a bit of a mark like the OPs picture and now I'm wondering if its acid but haven't seen any pics of this before.
https://www.youtube.com/watch?v=jY0bbRx3K64 [youtube]http://www.youtube.com/watch?v=jY0bbRx3K64[/youtube]
"Don't think that's is acid marks, most of the bars are born like that". That is fairly new style bar. Nowadays new methods of testing being use. XRF testing for example. Even though people do use acid to test them, drill them, hacked saw them. What is the good of the bar after that? Only dumb people will let the potential buyer does that to the bar. Will they buys it after the testing? Personally, I wont touch them, there are many bars out there, why would one buy it? unless it is one of this
If a buyer wants to conduct an acid test as the seller it is best to ensure that the price/deal has been agreed on and if the bullion in question passes the test it belongs to the buyer. ie no haggling after the test