How can I see my blacklists?

https://www.steamgifts.com/account/manage/blacklist

Also;
https://www.steamgifts.com/stats/personal/community
Scroll down this page.

Edit: You can ask this anybody who is mentioning a blacklist number though. I dont think it needs a thread on its own.

For example, you cannot join the target GA you have put on the block list.
For example, you cannot join the GA of the person who put you on the block list.

Buttons that can make the world smaller.
It's also a good idea to think before pressing the button. Click? ( *･Θ･)σ凸

And you can see how many you have been blacklisted here.
Stats - Personal - Community
https://www.steamgifts.com/stats/personal/community

The ESGST extension has the option to check users to see if they put you on their blacklist. It's a slow process unless you have an idea of who to check

Once you have the extension it's switched on in this section of options - 7. Users > 22. [SG] Whitelist/Blacklist Checker

Pro-tip: just having "blacklist" in a thread title is a sure way to get more blacklists. People seem to be ticked off by that topic.

Tip #2 about blacklist: Forget they exist. You'll be happier.
You can't control who blacklists you or why. They bar themselves from winning GAs so the best way to get back at them is to make awesome GAs and put them out of your mind.