Flies also need effects

I am not a beast
But I am more savage than a beast
Because I'm more greedy
Among the most extinct animals

Whatever I see
Whatever I smell
Whatever I feel
Always inspires my taste

Is it clean or dirty
Is it fragrant or rotten
Whether it is rubbish or carrion
Even though I brush with pleasure

I'm everywhere
Be an enemy of anyone
Both animals and humans
Because I am a fly