I do not think it is rude or bad etiquette to ask for the reserve. Some sellers are fine with disclosing it while others are not. I start most of my auctions at $1 with no reserve and am rarely disappointed with the sale price. I've found that this generates interest in the auction and competition among bidders determined to win the item. In many cases, the item sells for more than expected. I would only use a reserve if I were selling reluctantly and absolutely didn't want to sell below a certain price.