I wouldn't think that truly mysterious grab bags would be very profitable for you.
Just my hunch.
If you don't want to take the time to get IDs, you could sell them in random lots and might do well, but I think taking the time for a picture or two would help the sales there.
I _could_ be wrong. Maybe folks would like to take a chance. But considering how many common and modern marbles there are, it would be a big gamble for a buyer.
I don't know what an optimal lot size would be. Things have changed since I last sold marbles on a regular basis. But my suggestion would be to sell many lots at once (thought not all ending at the same minute), to try to encourage people to bid on multiple auctions. And offer a good shipping discount if people buy more than one lot.