I think passing is a tough subject. My personal style is clean passes only. I am generally a good bit faster than a lot of the other guys in my class simply because I wait for my chance. I like to run clean lines and make nice passes. I think it takes a lot more skill to be able to do that.
I definitly appreciate when other drivers also run with that style. I think that rubbing and using other drivers to help you run lines is kind of dirty. I can't stand when someone consistantly comes into corners too hot and take you out in an attempt to pass you. Not only does it ruin your lap, but you also run the risk of breakage because of someone else being inconsiderate.
On the subject of blocking, it's not always a bad thing. If I come up on a back-marker and second place catches me, I'll try to run certain lines to force others to "block" for me. I try not to bump and rub, but instead try to take up as much room so that #2 can't fit around us until I can pass the lapper.
If I rub someone, whether they spun out first or not, I tend to wait for them if we were in a close battle. I enjoy the competition and want to win because I beat you, I don't want to win because of something that might be considered remotly dirty, because then you have something else to blame.
On the other hand, rubbing is part of racing. I don't mind the occasional bump and I do sometimes put one on others, but as long as it's not a part of your racing plan and not consistant, I can accept it. If it starts happening race after race, week after week, then there's an issue with your ability.
At my track, we run an 8 week series, with the lowest 3 scores thrown out. That rewards week to week consistancy and clean racing makes you consistant.