Sometimes if you know a few things about programming you can see mistakes other programmers have made. You could probably even find them in the code if you had it for review. A great example is of an email I got today from someone who supposedly saw me on a website. I'd assume this website was a dating site had the variable not been empty when the email went out.
It looks like I must have been hanging out on the site called () or perhaps I'm supposed to insert something in there depending on my own online dating habits. Or perhaps the programmer isn't parsing his junk properly or maybe they got my name from some data mining source and there wasn't anything in the dating site: field so it came up blank. Interestingly the parenthesis were included in the email. In the spirit of this post I was going to include a picture of a shirt I once bought that had a very 1950s Hollywood TV looking blond woman with a tear in her eye and the caption said "I can't believe I didn't declare my variables". Funny but the t-shirt is now gone and apparently any trace of the design on the Internet has gone missing as well.