Zola claimed his principles of link exchange. I sumrized his ideas as following and my comments added as well [C]:

1. Friends sharing similar interests are welcomed.

C: I might misinterpreted/mistranslated this item here. What he used is a Chinese idiom known as "Zhi Tong Dao He" [literally means Wills Same Road Joins], which can be translated into "in the same camp".

2. Make sure your blog has CONTENT.

C: I totally agree. That's also one of the critera on which I blogroll blogs/websites [there are exceptions too]. CONTENT here doens't mean you have to be a good writer or commentor and come up with a lot of wonderful ideas in every post [come on it's blog!]. Anything original and interesting is worth reading. Even the trivials in life are worth reading as long as they are unique and narrated in a fun way.

3. Your blog should not be cramed with crappy content or rumors. Copy + Paste doesn't make sense. Spend more time writing down your own idea and tell your stories. Make me believe you are a friend from whom I can learn.

C: IMHO, it's indeed the elaboration of item 2. I don't reject copycats--on the condition that you are sure it's something worthy. Some bloggers filter content on the Web for us and they do have good tastes. That's good. And it's better that they comment on their choices.

4. Use TrackBack Ping when possible. No off-topic comments allowed. I think chatting in comments is a waste of time.

C: Agree. That's also what I indicate in the comment area. I do respect my visitors' freedom of speech but I also hope it is regarding the topic we are discussing. I don't want to be a gatekeeper but if there is anything inappropriate, I would not be hesitant to delete it. I hope my blog would be focused and work as a place to exchange IDEAS.

5. Text links on the frontpage only. I don't maintain a single page to store links upon request. I won't have time to read through them all.

C: I am thinking of adding a link page on my blog. My blogroll is getting longer and longer and some day it will mess my layout up. Might start working on that in the coming winter vacation.

6. The blog types I prefer are computer-Intenret related, politics, economics, management, law, arts, geography...etc. I prefer those original ones.

C: Since I don't encourage link exchange, no comment on this. I love original blogs too.

The uppermost criterion by which I link blogs/websites is whether I like it. You may notice my collections are quite different from each other in terms of content but they do share one--I love them all. Some might please my eyes; some might please my mind. The blogroll is indeed my bookmark and I visit my favorites via it. I add those valuable links only which I think will lead my visitors to a good experience. That's the only way I can care for my guests and I believe a good link is a wonderful gift.

IMHO, checking out a blogger's blogroll is a way to peek at his/her taste [will you like a guy who enjoy collecting junk? Well I know one man's junk might another's treasure. I mean real crap here]. What s/he links exhibits what s/he appreciates. I often find out some interesting blogs through the links on blogs I like. I do trust the tastes of my favorite bloggers and they never let me down [so far]. I can understand some bloggers exchange links to promote traffic and I do respect their rights to do that. Hopefully it's a win-win game as it is supposed to be.

I am thankful for those who link me. If the linking is based on reasonable judgment, I think it's a reward I should be proud of. If it's just the start of reciprocal link exchange, I would say "thank you" as well but reserve my rights not to link it. If your blog is interesting enough, I will link you unconditionally--you don't have to have a high PageRank, you don't have to link me back as a return, you don't have to... That's my way. If you link me in expectation that I will link you while I don't, please don't freak out. It's up to you to keep the link or delete it. I do value those who value my stuff instead of potential traffic from me.

Why do I oppose link exchange? In fact, I can't deny link exchange sometimes works fine but I am against IRRESPONSIBLE link exchange. That means you approve all the linking requests without scrutinizing the links beforehand. That's very dangerous. First off, I don't think it is ethical for bloggers to link the blogs they don't like themselves in exchange of traffic. As for me, links are more than links. They are indeed recommendations you make for you readers. If you don't like the blog, why do you expect your visitors will like it? You may argue that it's just an option and visiors are free not to click the links. Or it is still possible that your readers will LOVE what you HATE. However they do run the risks that be annoyed by your inresponsible links right? You also run the risk of losing them forever.

Secondly, I don't think the traffic brought by blind link exchange is of great value. It is no different from cheating by adding irrevalant keywords into your metadata to attract visitors. Do you think people duped by you will read through your website carefully and rate it 5 out of 5? Possible but no big chance. You might get some one-off visitors from links you exchanged, then what? They found no interst in you and will never come again. On the other hand, if your visitors are directed to some blogs they had thought might interest them but didn't, they will question your taste too. At least I do [I am mean].

So just be careful when linking and being linked. Your visitors deserve high-quality links. That's one of the ways you can pay back their support.