And don't they see me?
And then what if they put me in their friend circle, and then I have to be, you know, their friend?
edit: again, these aren't spammers or stalkers or people I don't like. They're just -- kind of annoying. Neither friend nor foe, I guess.
They will only see the things you post to public or to their circle. Don't do that.
If they put you in their friends circle, then their posts will be available to you to see, but you will only see them if you go to the circle you put them in. If you never go to the ignore circle or the all circles stream, you will never see their posts.
[Edit: Your real problem appears to be that you took a mere 45 seconds to judge a service that actually takes pains to address exactly your needs. Not only did you not pay attention to the tutorials that describe how things work or explore long enough to figure out, you also didn't check any of the readily available sources of information on the subject before not only making a hasty judgment but also deciding to broadcast your hasty judgment on a public forum.]
But it seems obvious to me that, in one or more ways, the people I don't really want to talk to will end up figuring out that I'm ignoring them. Let's put it this way. My status on Skype and Google chat is always "invisible". Always. It didn't seem like there was a way to do that on google+, and I didn't want to risk it.
As a matter of providing a constructive criticism, I don't see anything wrong with posting this to a public forum. This is the same note I sent them to explain why I deleted my account. I would like to start off invisible. I'd like no one to be able to see me unless I choose to see them. But that's not how the site operates (I'm not even sure it could function that way, if everyone did it) and so I'm making myself invisible in the only way I can.
It's certainly possible that someone you're ignoring will figure that out. I would imagine that's just the price you pay in cognitive dissonance for maintaining a relationship out of politeness. It's no different really from them eventually figuring out that you never invite them out to events, isn't it?
I'm not sure what you mean by invisibility. The service doesn't have presence except in gchat, which works exactly like gchat anywhere else, and you can set yourself to invisible. Outside of chat, if you don't post something into someone's circle, then you're invisible to them by default. Am I missing something?
They can see only your public posts, and posts you share with them or a circle they are in.
If they add you to their friend circle or their own ignore circle looks the same to you.
You can ignore individual people too.