You'll have to use your judgment in these kinds of situations, or look at the other safety tips to assist in the decision making process.

Review the people that fit your dating criteria; are the dating personals profiles well-written, or do they seem nonsensical?

If it's older than the current year, you may want to look elsewhere.

Browse around the dating personals site as much as you can without actually signing up.

Does the dating personals site you are browsing at have a privacy policy?