If you've never done that, how would you know VS helps you catch it! ;pThis has literally never happened.
(It helps that VS does auto indenting for you, which means that any second line added would jump back by one tab and alert me to the mistake. Er, not that I ever make them >.>)
I'm just OCD about it especially from when I worked on embedded systems stuff, where we had code standards and reviews intended to prevent those sorts of accidents, and we really didn't want something like an aircraft system having bugs like that. (We were also working in environments that didn't have Visual Studio, so fair point.)
Another one I like doing if possible is "if(SOME_CONSTANT == whateverVariable)" instead of the other way around. Dropping an '=' will result in a warning on some compilers the other way around, but this way dropping an '=' will produce an error on ALL compilers.
We also used the option to treat warnings as errors in order to force everyone to address warnings. I'd like to think this helped in some cases so people didn't just say eh, those warnings are probably fine.