I have found most people who will randomly add you as a friend just want to use you for their own gain later... Now we are pirates, and that does happen from time to time in the life of a pirate, but.... It is generally a good idea to only add people who you know, and have played the game with together at some point.
Once you have a giant friends list of random people, you will have people teleporting to you at the worst times.
1.) When you are sailing, they will teleport onto your ship while you are just sailing from one island to another, then fire on a Juggy, and it will sink you while you are just trying to complete a simple quest.
2.) You can be leveling, and bam there they are, taking all your rep. -or- They will attract a large enemy you cant defeat, and it will take you and them both out.
These are the two worst scenarios I have experienced time and time again as I played the game from my early stages. Be careful who you add as a friend. I have met some great people just randomly in an area offering me help, or me offering them a hand. The random friend, crew, guild invites are generally never worth it.
Larence Tuppington