I met a young woman wearing a paper mask, and after talking to her a little she lifted her mask and showed me a gash on her upper lip. She stated the woman who attacked her sprayed her face with pepper spray, and when she was coughing and hacking and couldn't see, the attacker used a knife and slashed her lip.
I recommended she visit guardmystuff.com because if the people who surround her are vicious and use weapons to attack, that she use the same weapons to defend herself. My point is you don't know who is capable of attacking you. You think you can read people and who you are safe being around, but the fact is that you never know.
In this situation the attacker used weapons to attack where they are truly meant for defense. Pepper spray is to disable the attacker so you can get away to a safe place. It is not supposed to be used to disable the victim so they cannot fight back, and stab or hit them. When used properly they are effective tools to carry with you, and prevent something very bad from happening to you. Essentially, it can save your life.
This doesn't mean that every person approaching you on the street deserves a spray in the face. If you are that afraid then you should go to self defense classes, and learn techniques to defend yourself. However, keeping articles on you like pepper spray or a stun gun will give you a sense of security that if someone dangerous does approach you, then you will be ready to defend yourself.
Pepper spray is easy to carry, and even comes disguised as lipstick. There are options that are a little more expensive, but they spray farther than the less expensive versions. It just depends on your needs. See the links below for some options.
I myself carry pepper spray in my car, and in my purse. Don't be caught in a situation like the woman with a gashed lip. She is scarred for the rest of her life.
Protect yourself.