Voiceovers and Narration

We were talking about narration today in class and the best kind of narration we said was when it came from the character in the past talking about his future or vice verser for example in American Beauty (seen below)

I learnt that there are certain ways to indicate that this is the voiceover in flesh, without physically pointing an arrow at the character. this can be done through a simple camera shot of the person getting dress and the narrator talking, the audience are obviously clever enough to work out that this is the narrator in the past or in the future.
What I really don't like is using the characters as narrators and getting them to break the 4th wall. This was done a lot in the 80's and 90's for example Malcom in the Middle and The Fresh Prince of Bel Air.
 Also a popular 80's show that broke the 4th wall is Saved by The Bell (seen below

I think when used properly you can break the 4th wall without it looking unprofessional and messy. I think when used in a comedy it can look fantastic but when used in say a horror film or a drama it looks amateur so my opinion is that to use a trick like this is very brave and can only be used professionally I would never use it in my own work.

CM