I propose a new forum topic, Worst Instructables.
My nomination for the first entry: using an Arduino output pin to power a Peltier module, in series with a resistor and an LED.
Redeeming social value: it won't destroy the Arduino, unlike some other Instructables.
I had to laugh at this comment in the code:
analogWrite(peltier, 120); // Look first on how much voltage your peltier unit can handle 255 = 5V
@jremington
What the … made You upset? Being experienced (old) and having seen a lot of stupidities, what made You soo upset?
Sorry, I'm to late in the day to follow up Your link. Can You outline, summarize, the matter?
Best reegards and respect.
Could fit in the bar next to the "Wall of Shame" thread.
But be careful or we'll end up with tutorials off this site in there with them.
There are indeed problems with some of the tutorials on this site, but few would be competitive with Instructables for the bottom of the heap.
Sorry, I'm to late in the day to follow up Your link
Tomorrow then. Have a nice night!
@jr
Yes, there are surely a lot of false profets out there.
I once commented a guy issuing his project on a sight. Because of some noice problems he feed 5 volt logic to a 3.3 volt device. I pointed out the mistake but the answer was:"It doesn't work wothout 5 volt"...
What the h--ll. Reading specs, designing according to worst case, has made some of my design almost classical.
OK, so it's "Idiotic Instructable of the Day" (or some three years ago) but let's face it - only today. 
The wafer is made of diodes in series, has a total forward voltage. All the ones I've had ran on 12V to move Watts of heat from one side to the other.
5V won't light 2 blue leds in series. Color requires voltage, brightness requires current.