Chrissy Teigen Explains Why She Was Bathing in 'Dirty' Bathwater

Chrissy Teigen had to explain why her bathwater looked dirty as hell after John Legend posted a video of her washing up ... and the explanation had already been spoken.

Here's the deal ... John recently posted a video of Chrissy sitting naked in a bathtub, using one of his skincare products to scrub off body makeup ... something she explicitly said in the clip from the get-go -- and yet, there was still some confusion/mockery over this.

Trolls quickly flooded the comments on John's Instagram post, saying the brownish bath water looked "dirty" ... and accusing Chrissy of not showering enough, etc.

Clearly, the haters missed the part of the video where Chrissy says what exactly she's scrubbing here ... because she's now in the comments offering up the same explanation.

Chrissy says .... "the water is dirty because I'm getting my body makeup off, like I said in the video my sweet angels!" Pretty patient response.

In addition to her comment section clarification, Chrissy clapped back at an account that tagged her in a post saying the "tub is for soaking not bathing."

Chrissy explains she was soaking her body makeup off before showering and adds ... "TUBS ARE NOT FOR BATHING, the internet is unhinged."