They're waterproof, just on the wrong side ... <G>
Mink oil is great for darker suede as long as you apply it properly. Trick is to put it on liberally using a shoe rag with a circular motion THEN immediately blot off as much of the oil as possible. This step is important to restore the nap. Repeat as necessary.
Lighter shades, maybe not? And blue suede? Yer on yer own there, but I'd suggest you'd lay offa dem blue suede shoes. ;-}