On your profile you have assigned a picture and if somebody adds you as a friend that is the picture which is used. However, the profile picture that is stored on your friends page (the thumb-nail picture that is next to your name) under ‘FRIENDS’ is the picture that was your profile picture at the time of becoming a friend. So if you became someone’s friend even before you had a profile picture then you’ll have a little grey blobby person, even if your profile picture is updated later. That means that if they have a grey blobby or some previous photo you can see that you bacame friends in that ‘era’ but it could mean that you will always have a grey blobby person as a friends profile picture. Example: when I became Tuner’s friend I had a different profile picture and that’s the one that remains in her friends:
In other early friends my profile picture is a grey blobby because I became thier friend before I had a profile picture. Probably the piece of code that updates the profile picture does not send the picture to all the places where it is used already but only is used for any new assignments. Anyway sorry to bore with that rather ‘propeller-head’ techy situation but I had to share it with someone.