I have not found any consistency when it comes to hogs, some are just bad. I have killed some right around 300 lbs and tasted great. Killed some boars right at 200 lbs and tasted great. I have killed some 30lbs and tasted bad. I havent figured it out. Some are bad and some arent.
I now just take a piece of meat and throw it right in the fire, if it smells like piss I throw the whole pig away. cause thats what the bad ones taste like, piss and you can smell it when you cook it too.