I don't know if this is how all labels are or not BUT the labels that my pharmacy uses has ink in them. It's like how most receipts are printed heat brings out the ink. So if I take a lighter or other heat source to my prescription label it releases the ink and the whole thing turns black and illegible. Hope that made sense.

There have been several exposes on TV about pharmacies just throwing bottles given to them in the trash. I know Wal-green's has gotten called out for it several times. I would never trust someone else to get rid of my labels.