system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: if there are a ton of harmful bacteria in every persons mouth, why is it relatively safe to give/receive oral when genitalia is so sensitive to foreign bacteria?
gpt
The bacteria in your mouth can cause harm depending on your diet and personal hygiene habits. They are also specialized at living in this environment and prevent harmful bacteria from taking residence in this nutrient rich environment. Along these lines - most of the time, most of the bacteria in your mouth are protective, not harmful.

It's a similar story with the vaginal microbiology. Specially adapted, usually protective.

When you swap bugs from one environment to another they don't do well. It would be like plunking a lion down in the Arctic.

Source: PhD Microbiologist, working in Oral Care 10+ years.