Criminal Sentence 13: Vague Subjects

From an online map service:

"When using any driving directions or map, it's a good idea to do a reality check and make sure the road still exists, watch out for construction, and follow all traffic safety precautions."

This is a typical misplaced modifier that involves a vague subject. The sentence starts off with "When using" but fails to state the implied subject: "you." As a result, what comes after the comma ("it") inadvertently--and incorrectly--becomes the subject of the sentence. It would be better to write "When you're using..."

In my book I call these "vague -ing" words. They're very common but no other writing book I've found covers them. Please be extra careful when you start a sentence like this. Always ensure that you state who is doing what.