If you have the techs that obsolete a given resource you can get if off another civ for free.

Example: I have Combustion and any Whale resources I have no longer give me bonuses, but if another civ has it I can put it on the trade table and ask 'what will make this work?' and they won't ask anything for it. When I check my cities I am getting the happiness bonuses for these resources.

It's not a bug, that's how it works. Retroactive happiness is just something that happens in Civilization IV.

The valuation should be considered a bug. The current situation goes something like this:

"We used to sell you this resource for 10gpt, but now that it's obsolete and you can't possibly harvest it yourself, we'll give it to you for free"

That might make sense if you couldn't make use of it, but since you do still gain the happiness benefits, the cost should be at least as much as it used to be, if not more.

The valuation should be considered a bug. The current situation goes something like this:

"We used to sell you this resource for 10gpt, but now that it's obsolete and you can't possibly harvest it yourself, we'll give it to you for free"

That might make sense if you couldn't make use of it, but since you do still gain the happiness benefits, the cost should be at least as much as it used to be, if not more.

I agree. It's like the price of ivory plummeting after the poaching ban, makes no sense at all. If anything the price should go up(though realistically, you shouldn't be able to make use of Ivory/Whale at all).

OH NO YOU HAVE +1 to +3 HAPPY FACES IN YOUR CITIES.

Seriously, once they obsolete, you have so many other ways of getting happiness that its negligible at best.