The way my website treats products is hurting SEO

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

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  Michael Martinez: Is there a legal reason for doing this? Maybe they have no choice?
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  Joe Coville: Michael not that I’m aware of. It’s just a half baked system.
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  Joe Coville: when I say vehicle I should clarify I sell trailers. It’s very glamorous.
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  Michael Martinez: There is often a business reason for Website behavior that doesn`t make any sense to an SEO specialist. If you`ve investigated and found no business reason for deleting those listings, then I think your idea to reuse the pages is sensible.
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  Perry Bernard: Relating it to a vehicle site i helped with, we preserved vehicles for up to 6 months in a “sold recently” category and added a sold banner to the images. This preserved the URL and all listings for up to 6 month lifetime. Once they matured, we set a redirect to their pages with same brand and type. So a retail site with 400 cars almost always had up to 2000 listings. FWIW google liked it and lifted rank sitewide.
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  Adam J. Humphreys: Some auditors say delete but I would say a specific redirect to the category page of that exact vehicle would be more productive by a lot.
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  Greg Gifford: Adam is right. A few things at play here. In most states, it’s a legal thing. Keeping a sold car live on the site is considered bait and switch advertising, since you’re listing a vehicle that is not available. And it’s a user issue too. If someone is looking for something and they land on that page and see it’s been sold, they don’t stay and browse, they bail to another site to find what they’re looking for. Best answer is to land them on a category page with a simple message at the top that says the vehicle they were looking for has been sold, but here are similar options
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  Richard Hearne: Yeah, this is a problem that many classified sites face - do you remove a listing once the item is sold, and if so do you 404 or redirect. From a user perspective, it can often (but not always) be a poor user experience to land on a product listing which is no longer being offered. It can make sense to retain historic listings if price discovery is something users want. But generally speaking you expect removed listings to decay (404). Some sites like to redirect listings into their parent category, but the efficacy of that is unknown/disputed. You can also update older listings to include messaging/links to similar available vehicles you have in inventory, but this can be hit-and-miss.From a pure SEO POV, yes you could be losing backlinks which pointed at inventory which is being removed. But that could be entirely offset by the damage retaining stale inventory/content on your site might cause. My money is on thinking how would this work best for your users, then looking to see how you can achieve that in the optimal SEO way. The bit I`m lost with - why would you change the VIN? It`s unique to the vehicle, so you shouldn`t change it IMO.
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  Federica Baiada: I`d create an ah hoc 404 page to inform customers of the changes and maybe use it in an engaging way to redirect customer to a relative page (if any, obviously).