What I’m saying though is if you did write a post about hiking on your photography blog the search engines would have no problem with that. They would still rightly see your site as being much more about photography than hiking though. And they’d be right. Topically your site would still be more about taking pictures than hiking. That one post would be more topically relevant to hiking, but the site as a whole still wouldn’t and shouldn’t be classified as being about hiking.

Why is that a bad thing? Should a site that writes one post about a subject be seen as more on topic than a site that writes about the subject every day?

I think search engines are a lot smarter about understanding relevance than you might think. I agree at the moment a human being is going to see the connections more easily and a search engine will miss some things that are related, but from the search engine perspective their concern is how to rank a given page.

Should a site that mainly writes about photography start ranking for hiking related terms because of a single post?

The main thing that strikes me is that two concepts that are obviously related to a human – say landscape photography and rain gear – probably won’t seem related to a computer algorithm. Even sometimes two concepts will seem related to one person but not another … I developed a blood clot in my leg working too much. I could see making a post about hiking, having to explain to the reader why I didn’t make it very far from the trailhead, or why I didn’t go up to the timberline, because my doctor – insert link here – told me to stay at or below about 5,000 feet until this is solved.

It’s not that I’m worried about being caught and punished, because from everything I’ve learned about search optimization and TOS, I’m not doing anything wrong. I pay for my camera gear as a software developer, so at times I get too hung up on the details, because writing code is all details. And maybe that’s what’s going on here?

Think of it like this. You have a site that’s clearly about photography. That’s what you right about and that’s what you optimize the site for and most of the sites that link to your are also about photography.

Now lets say Gore Associates links to you. Gore probably has some decent authority with search engines so you get an authority link. But you wouldn’t expect your site to all of a sudden start ranking for hiking related phrases. And it shouldn’t. While you may mention it from time to time odds are someone search for hiking boots isn’t really looking for your site. Still the link from Gore gives you some general or global authority to help you rank better for photography phrases.

Taking it further pretend you start writing more and more about hiking. Maybe you have articles on what you wear or the best places to hike in Seattle or reviews on tents. You start picking up more links from sites that are seen as hiking sites. You would start picking up more topical relevance to hiking and some of your pages might start ranking well for hiking related phrases.

I think your looking at topical relevance in the sense of reciprocal links and thinking the search engines are going to frown upon you linking to Gore and them linking back to you. They won’t. The issue with reciprocal links is when the majority of your links are directly exchanged with other sites and there’s no topical relevance at all between the majority.

I’m glad you like the list of links. I’m trying to change who I link to little by little so I can feature sites and blogs that don’t get all the coverage, but really are just as deserving of been seen and read.

“Topical Relevance” is getting really overblown. Say there was a landscape photographer in the Pacific Northwest who decided to link to Gore Associates, in Maryland, in a blog post. Again, what does purdy pichas have to do with a plastics company on the East Coast…? Well, it rains a lot in Seattle and GA makes Gore-Tex. Photography involves hiking, and I give out advice on technique, location, and gear. Why it’s relevant would be obvious to a human reader, but less so to any code I’d be able to write.

You’ve written a really extensive list here. I’ve already spotted a few headlines which I’m about to go click, so thanks!