It takes basically nothing to run a blacklist. You're pretty much free to do whatever the hell you want with one.

You'd be hard-pressed to find an IP that isn't listed in at least one blacklist... for example, my latest favorite is the blacklist that lists anyone sending commercial IPs. For example, send your customers an invoice? They'll list you. Send them an order confirmation? Listed again.

The real test, is are you seeing email being rejected? If not, then you're probably just listed on some very low quality blacklists.