Great inputs!

But what if, for legal reasons (price, pictures, etc), the ad has to be removed after it has expired. (real case here)

Ideas:

1. Modify the ad page and return a 200? (remove ad data and add a message saying it's expired)
2. Throw a friendly 404 page, saying the ad has expired and show other options for the user to navigate to
3. 301 to it's parent page

(3) is my favourite, but (2) may be the best option for users.

Thoughts?

I don't think there is a definitive answer to this, but worth the discussion:

How to handle an expired ad in a classified / auction site?

Michael Gray mentioned you should 301 it to it's category page, and I'm inclined to agree with him. But some analysts say you should return a "product/ad expired" page with a 404.

For the user I think the 404 aproach is best, but from a SEO perspective that means I'm throwing link juice out.

What if I 301 him from the ad, and show a message saying why they're seeing the listing page instead of the product page?

Thoughts?