Man, they don't like to give up those limes, do they?
I worked in a bar and the lime slices were probably the most unsanitary items in the whole place. They sit out in the open all day and at closing time, they are shoved into the refrigerator and taken back out the next day. You do not want to ask for a lime slice in your drink, trust me on that! On the positive side, the alcohol in your drink will likely kill most of the germs so I guess it’s not that big of a deal.