But what about when the URL slug gets really, really long?

Selected answers from the Dumb SEO Questions Facebook & G+ community.

• 
  Andres Riobueno: Not an ecommerce guy but it depends on the size of the site. Some of the sites we manage have URLs that are somewhat lenghtly. You should be fine as long as you make those URLs accesible through your top nav or left nav (if you have one). I`m missing a ton of context here but you could have that subcategory link in the top nav and call it a day.
• 
  Alan Bleiweiss: /categoryname/subcategoryname/product-name IS the cleanest URL structure and syntax. 1. It`s the best way to convey to any humans that see the URL where on the site the page is, and what the product is all about as relates to its parent and grandparent groups. Same is true for search algorithms. This can get ugly of course, but only if spamming keywords into each silo level in sequence.
• 
  Michael Stricker: Common Ecommerce practice puts /product back at the top-level again, for a shallow architecture, so /cat/sub-cat but /product — this is especially effective when /gender/Dept/Cat/Sub-Cat/sub-sub-Cat intervenes, causing unwieldy URLs that exceed 100-115 characters.
• 
  Marcus Pentzek: Hey Brian, /category/subcategory/productname is not a rediciously long URL structure but a very clean and easily understandable one ;-) In most cases I`d go with that one. There might be situations though putting products down on /p/productname might make sense. For example if your products being to many cats/subcategories which would create many duplicate product URLs (canonical looks like a solution, but often doesn`t work as expected)
• 
  Zoran Jozić: As Alan Bleiweiss said, /categoryname/subcategoryname/product-name is the cleanest URL structure and syntax, but it may get rather lengthy from time to time. In my opinion, to remedy this problem you may omit either a subcategory or even a category. To help people understand where the page is compared to the rest of the site, you will use the breadcrumbs. No need to do it twice, in the URL and the BC. In normal circumstances you`d do it, but in this situation, it`s a trade off.
• 
  Stockbridge Truslow: I`m with Alan on this one for sure. /cat/sub-cat/product-name. In addition to the points he`s made above, there`s another thing that goes on in there. Let`s say you have several different sizes of widgets available for sale. Each one is its own product on the site. /widgets/customized/small /widgets/customized/large Now, someone searches for "customized widgets" - so which page does Google send you to? The small or the large? Which this type of structure, Google doesn`t have to pick one - it knows that if it sends you to /widgets/customized/ that you`ll be presented with both the small and large (and any other) available types of customized widgets. If everything is up at the top level, then it`s hard to determine which level to send the user to when Google doesn`t know exactly what they`re looking for, but has a general idea. You can ultimately go as deep as you need to, but try not to go deeper than you need. I`ve found that the magic number is typically about 20. Once I have 20 products in a category, I look at them and see how I can break them down into 2-3 more specific sub categories. If I have less then 3-4 products in any bottom category, I consider maybe combining them with another category. Users don`t like to drill down and find nothing, there - but they also have trouble when they are overwhelmed by too many choices - especially if most of them aren`t what they are really looking for. For cleaning up the structure - get rid of redundant words where possible. In my example above, I could have done "widgets/customized-widgets/" but since I`ve already used the word widget in the level above, the user (and Google) can assume that whatever categories appear below widgets are types of widgets - no real need to repeat it. Same with the product name. If the full name is in the title, it`s (usually - though there are certainly exceptions) okay to just give it a short name. In fact, for the URL, I tend to give it the SKU number, not the name. The product name is in the page title so it doesn`t hurt much in the grand scheme of things to give it a shorter url like /widgets/customized/SM-X2 rather than /widgets/customize/SM-X2-all-purpose-customized-small-widget.
• 
  Kim Krause Berg: And...if you are creating navigation for all those levels, take mobile design into consideration. Drop down menus on mobile are hideous for UX with multiple levels. Alan Bleiweiss has it right.