Feeling uneasy spamming people

I am following the suggestions several people gave me on how to get involved in DW. I am checking out people linked from the comments to that post and some other posts I made. Reading some of their entries commenting on those entries I find some interesting and marking them as being in my circle. Then I follow some more links from their posts and do the whole thing again recursively.

But I feel uneasy commenting on blogs of total strangers and marking people quite randomly. Why them and not some others from the other 6 billion out there?
I don't know them personally. I don't even know them online. Maybe I read a few lines they wrote, but then what?
That does not really give me any right to just push my unwanted words on them.

I have my own blog elsewhere where I have been writing for 3 years or so but that was strictly professional. I was commenting on other peoples blogs but those were professional entries as well.

I guess I am uneasy with getting too personal with total strangers.