Having the same issue now with an Asda chicken. Have supermarkets discovered a new preservative or something? It’s beyond a joke. It smells foul, unappetising (but not rotten) as it’s cooking. I won’t want to eat it. I also bought some beef from Asda but they delivered the wrong size and are supposed to be replacing it. See how that turns out.
Update: Asda never replaced the meat yet, and on the theory that supermarkets have to disclose preservative/irradiation on the packaging I ended up with a gammon. I guessed (might be wrong) that it’s something they sprayed on fresh meat to kill germs over the festive season when the shops shut for days. It smelled a lot like toilet cleaner (without the pine), whatever it was. The gammon was fine.