Unsuprisingly, given the wide range of projects possible using the GPIO, I regularly come across questions where someone can't get a part of their GPIO related project to work.
Normally these sorts of questions come from new users, and they have often taken the the time to post their code, or the relevant section of code. However, they normally fail to post a picture/diagram of their circuit and how it is connected to the GPIO.
This tends to prompt me, (or it has already prompted someone else), to write a comment telling the user to include a picture of their setup.
My question is how useful is them posting a picture/diagram of the circuit to answering their question? And what are some obvious clues that the problem lies with the code rather than the circuit, which would then help to diagnose the problem.