To add to AmericanEnglishCoach's answer, I'll mention about "bad habits". While vice is used for the more technically/clinically addictive "habits" (like excessive drinking, smoking, gambling etc...), the term "bad habit" would generally refer to more "personal/petty" unwanted habits like biting one's nails, scratching in hmmm...(get it?); staying up late too often or getting immune to your alarm clock.^^

Oops, I made a typo in my response. Please read and as an. ;-) Janine AmericanEnglishCoach

Thank you everyone!

@matt7988: That's part of learning. Even paying attention to what others may consider insignificant. A lot of people nowadays just don't admit they have vices; so we do a lot of euphemism to soften our "guilty pleasures". That's why it (the word "vice") doesn't get used so often.^^

Despite what others have said, trust me, vice is not a commonly used word. I don't even remember the last time I had to use it in a sentence that way, if ever. Don't think too much into this.