I hate to break it to you, but your bath towel is dirty – really dirty.
The moment you use it, it becomes a breeding ground of bacteria; fungi; dead skincells; salivary, anal and urinary secretions; and many other germs lingering in your bathroom that may have hopped onto your towel – including droplets fromyour toilet.
While most of these microbes aren't likely to harm you, given that most of them probably came from your own body, they're there, and they're multiplying quickly.
When you wick moisture from your body, the microbes and other secretions such as cellular debris that live on the surface of your body get deposited onto your towel.
It's hard to say whether the microbes growing on your towel are harmful, since most germs in our households aren't dangerous.