I’ve recently began noticing some pretty deplorable practices that some do when providing outbound links. Instead of providing a direct link to a site they instead utilize redirects. This allows the visitor to get to the site when the link is clicked but does not allow the search engine to follow the link. Therefore the link is essentially not a link that can be counted for a site’s link popularity.
One site I saw recently went so far to mask their redirect by using the ‘onmouseover’ to make the browser display the URL in the bottom left corner (place your mouse here for example) when you mouse over, masking the redirect.
Let me say in no uncertain terms: this is lousy, shady, and deceitful. If you agree to swap links with another site but do not provide a link that can be spidered by the search engines (assuming you do not disclose this fact before hand) you are misrepresenting what you are providing. Someone who cannot be trusted with something as simple as a link certainly cannot be trusted with my purchase of their product or service.
Regarding linking, I believe fully in providing quality and not seeking ways to cheat the other site by giving them less than they are giving you. With that said, I believe link swaps are on their way out and you should focus on getting and giving quality one-way links to sites that complement yours.