Pig shit consistency, like most animal by-products, varies in accordance to the diet. It does, however, stink unlike anything else on earth (except maybe a vulture) and it has one of those palpable odours that seems to cling. Therefore 'thick as pig shit' would depend entirely on what you feed your pig.

To be happy as a pig in shit probably refers to the animals habit of rolling in mud and (as they don't have WC facilities) shit to protect itself from the sun. Pigs do not have sweat glands so the phrase 'sweating like a pig' is misplaced. That phrase refers to the fat 'sweating' out of a joint of pork when it's being cooked. To prevent sunburn, piggies roll in mud. Mud is made of dirt and liquid. When water is not available, this liquid can be urine. Urine smells. The pig rolls in it and gives the impression it is covered in shit. The pig is content because it will now not become pork crackling before its time.

This is why it is important to a) provide the pig with a good supply of dirt and water, b) provide the pig with shelter from the sun and c) put the pigsty well downward of the prevailing wind.

LTS