It's already happened to me twice in the last 6 months.  Someone shows up at your door claiming to be from DTE and asking for you to show them your bill so they can confirm something.  They want to take a photo of your bill and/or get your phone number.

WXYZ reached out to DTE and confirmed that these people are not DTE employees, nor are they contracted workers from DTE.  They also received a statement from DTE about how to avoid possible scams.  You can read about that here.

The best thing to do is to ask for identification proving that they are affiliated with DTE.  And when they cannot produce the ID, just close the door on them and maybe even threaten to call the police (you don't actually have to, but it's perfectly OK if you do) so that they might be scared off and not bother your neighbors.