The phrase sweating like a pig probably comes from the American South, where pigs were raised by people and eaten. Pigs ate food scraps and licked sweat off their faces to cool down in hot weather. The practice of eating pork actually dates back thousands of years, but was not popular until the 18th century when it became fashionable for wealthy Americans to eat bacon every day.
Why don’t we just say “sweating”? Isn’t that more accurate?
Bacteria use sweat-like substances called electrolytes to travel across membranes in order to make cell walls stiffer and easier for them to travel through without completely dissolving (for example, when they move into areas filled with water or alcohol). Sweat is produced by glands in two different locations: beneath your skin on your feet and palms; under the surface of your tongue; along hair follicles; inside small blisters at points such as between toes (plantar hyperkeratosis); behind ears (auricular hyperkeratosis) or around fingernails (onychodystrophy). If you’ve ever had athlete’s foot then you’ve encountered this type of bacteria that can be found anywhere there are subcutaneous glands. So yes, bacteria are capable of traveling through these paths even if they’re difficult for us human beings too! That doesn’t mean it’s “more” likely that they’ll get transferred though–it means it allows them access.