Recently purchased this Keys BH1750 light sensor from an eBay supplier:
As you can see, the supplied cable will only fit one way. The Vcc wire, which connects to pin 1, is coloured red and the Gnd wire is black. All as you would expect. But look at this other picture from the eBay page:
In this picture, the wire colour sequence is different from the first picture. This time, brown is Gnd.
And here is the one I received:
As you can see, the wire has been manufactured incorrectly and colours are reversed, compared to the first picture above. Vcc is the yellow wire and Gnd is brown. Red wire is Addr and black wire is SCL.
I did not notice this at first, and initially thought my sensor was faulty because it was not responding to i2c scanner sketch. Then I noticed that the board was hot!
Once I had figured this out and connected the wires correctly, the sensor seems to have survived and works OK. But another minute could have killed it.