It's my seventh sense.
I'll read it as long as it doesn't take any real amount of effort.
Two things influence my decision to start reading a thread: the thread poster and the thread topic. If the topic catches my eye, I'll read it no matter who started it. If a thread was posted by a person whose posts I especially enjoy reading, I'll read it regardless of the topic. Most times, I read a thread based on a combination of these two factors.
Once I have started reading a thread, I will generally read all of the posts in it. I may skip really long posts that don't interest me, but for the most part I don't skip anything.
If I start reading a thread, and the first post doesn't bore me, I'll finish it. I don't discriminate based on any factors. I just have a laugh at the idiotic posts :D
i don't not read posts made by people i don't recognise, i just enjoy reading posts from prominent members more because i have an idea of what they're like, etc.
I read the first half of the post then continue scrolling unless it was an interesting post (god forbid)
Naw, not really. Sometimes it can go in one ear and out the other, if I don't care enough.
I don't discriminate in any way with regards to users when I'm reading a thread - at least, I don't think I do, anyway! However, there have been occasions that I'll disregard posts based on how long they were.
EDIT: So pretty much the same as what eest said.
I tend to read whichever posts are new in specific forums, but I do not read based on popularity of people. I've been here for a long time and that is the way I have always done it.
Now that I look at who has responded in this thread, I recognise all but one of them so it would be hard to find posts to skip if I did this. xD