One way to look at a link out of your site is to look at the value that you are receiving in return for your valuable link to them. The value may be direct or indirect as traffic or link juice (page rank), or indirect which is perception . Which I guess at best is an endorsement type link say from an authority like the front page of a CNN news story.
The two are theoretically supposed to be one in the same but it often does not always work that way.
The most important aspect of a link is by far the traffic or link juice which helps to build the "worthiness" of your site for ranking in the eyes of the engines.
Why I do not like link exchanges:
1. It uglifies your site.
2. Algorithmically it has drastic diminishing returns when you stop trading.Almost rendering months of work, worthless.
3. A link out is a leak of page rank. So it had better be a tremendous site that you link to. You will still bleed juice but perhaps the resource is worth it (I hardly ever find this to be true)
4. The chance of getting traffic from the other sites page which is usually buried and not of much interest to their visitors is extremely low.
5. It is very hard to monitor for cheaters. It is very easy to game you. No follow links & java script links look real to the human but do not pass any juice to your site.
6.When you are actively building your own 1 way inbound link juice, any links out are sure to help your partner more than you.
This is not to say I don't do exchanges but you will have to joining the http://realestateguerilla.com/ online coaching club to find out when I find it worthwhile. Notice that I did not mention that Google will penalize you for an exchange. That is an urban myth and I have seen too many sites rank well that still trade links.
