Google Reader Sharing

I've been using Google Reader now for several years, but the recent changes incorporating sharing with Google+ have left me at a loss as to how I can define my circles so that only those persons who are interested in seeing my shared items will be troubled with them. I read a variety of blogs. Not all of these blogs are genealogy-related. I know that many people will not care to read many of the topics in my feeds, yet I struggle to know which persons really do want to read them. With the old Google Reader, only my close friends who followed me received my posts. Now with the circles feature, everyone in a circle receives something. I've considered various options such as creating a circle of only persons in a circle who express interest in posts, but that might leave some people who really want to see these out. Another is to just send it to everyone in a circle that is defined for the topic (such as genealogy); however, some might consider it SPAM particularly if they've already read the post through their reader. How do I know which genealogists also share other interests and might be interested in being added to a circle of another interest? Another option is to abandon use of sharing altogether. I really think that Google+ really didn't think this change through before implementation. I'm curious as to how others are handling this sharing -- or have you just abandoned sharing?