I fully agree with the other answers, however there is something else to think about here.
Whenever you edit a post, it gets bumped to the top of the hot questions page, where it hogs the attention. This is a good thing for posts with some value, but bumping mediocre questions for trivial edits robs better posts of the attention they deserve.
Depending on the site, there are usually 40-something posts in the Top Questions (43 on MSE, 90+ on SO and 48 on all others I frequent). For a hypothetical example lets say that eight 2k+ users edit just one old "OK, but not great" question. Add four mediocre questions from new users (really bad ones vanish pretty fast) and you have a Top Questions list 25% made up of mediocre questions. If, however, it is an answer to a good question, the question is worth bumping and improvements to its answers will be a good thing.
On more technology-oriented sites where information ages very quickly, bumping old questions which are no longer relevant, outdated, or incorrect can also have negative consequences. Someone might not realise that the question is obsolete, leading to confusion.
In summary, I suggest making sure a question is worth bumping before doing a minor edit.
Here is an old question of mine in a similar vein. It got some high-quality answers which are relevant to this discussion, and may be helpful.
Should I edit posts that have one or more important words spelled incorrectly?