I sometimes receive spam to special email addresses that I only use at particular sites. For example, I just received one to an address I used only ever used to experiment with the game Town of Salem, years ago.
When this happens I assume that my address was sold, or the site was hacked. In either case it reflects badly. Is there a registry somewhere to collect sites that sell/leak email addresses?
Note that the above example is just one of many. I assume the ToS of some permit selling email addresses. In many cases, such as the RadioReference hack, this isn't the issue and should be made public.