Editing questions, apparently a lot of contributors improve readability of code samples, not only correcting whitespace. Their edits make use of their domain knowledge. E.g. upper and lower case in Apex and SOQL like here:
While I agree it improves readability, I tend to dislike such measures. (I'm currently skipping such cases.) It makes it more likely to introduce errors. It is often inconsistent.
In addition to that the proofreader changes the code necessarily without explanation, if she/he changes the code at all. The original author might not understand this change.
On the other hand I've modified cited code myself. E.g. I've added "S" at the beginning of a code example, because due to copy/paste sloppiness it started "tring s = 'something'".
Where do you draw the line?