I want you to help me figure out what this is about. Please.

Greetings detectives,
Here are two images showing two different events. The person who took these pictures claims that they used the bathroom for the last time at night and prior to leaving they didn’t see the marks but they saw the marks the next morning prior to using the toilet again. Let’s (for now) assume that this person’s claims are true, and one of those claims is that no one else uses that bathroom. The black marks can be wiped off. Your task is to tackle what those dark marks are, please and thank you.
https://s3.postimg.org/nqnj66pqb/14054821_10208210280387688_1811702497_n.jpg
https://s3.postimg.org/xz6om2i5f/14054777_10208210280467690_1562197165_n.jpg

Someone with a fat filthy butt snuck in and used the facilities.
Could be worse.
At least they flushed.
:slight_smile:

That or the person who took the photos hadn’t showered in a few days and bacteria grew on the toilet seat overnight. Not a very interesting mystery, frankly.

Greetings detectives, Here are two images showing two different events. The person who took these pictures claims that they used the bathroom for the last time at night and prior to leaving they didn't see the marks but they saw the marks the next morning prior to using the toilet again. Let's (for now) assume that this person's claims are true, and one of those claims is that no one else uses that bathroom. The black marks can be wiped off. Your task is to tackle what those dark marks are, please and thank you. https://s3.postimg.org/nqnj66pqb/14054821_10208210280387688_1811702497_n.jpg https://s3.postimg.org/xz6om2i5f/14054777_10208210280467690_1562197165_n.jpg
Mold. It can be invisible but can grow in a few hours. Bleach will usually kill the spores. No mystery at all. It's fairly common.

The reason I question the mold thing is that I think it generally doesn’t grow on toilet seats, but inside of toilets. No?

Key word being “usually.” Could also be left over dirt and sweat.