Let's say I call up another agent who has a nice website and offer to link to write a post on my real estate site's blog and dofollow link to them with their preferred anchor text. Maybe focus on some activity the area is known for, like eating fresh lobster if the other agent was in Maine, or skiing/snowboarding if the other agent as in Colorado.
I would then ask for a link back from them of course.
Now while I would take the time to create a blog post as agreed and then contact them once it was live, my guess is that a good number of them would simply put my link in the sidebar of their site or something thus I would get credit from their homepage. They're probably not going to write a blog post to link back.
So how would this play out where SEO is concerned? There is obvious two-way linking here, as they are linking to me and I am linking to them...but if they get a blog link that will live on an individual blog post and I get a homepage link...wouldn't I be getting the better end of the deal?