Here's my take on the topic.
Good friend: A person who's company you enjoy and one you can confide in. A good friend will always bring out the best in you and want the best for you. A true friend will not hesitate in correcting you when you err, and encourage you when in the right. A good friend is a blessing and worth cherishing day and night.

A bad friend: The old saying applies here, with friends like this who needs enemies. Quite the opposite of a good friend and not worth keeping except only to benefit them. But yes always be on guard!!

Always pray for an abundance of good friends and seek refuge from the bad!