10 - Masterpiece anime I'll never forget about
9 - Became a personal favorite
8 - It's good and would recommend to anyone
7 - It's good but wouldn't recommend / Niche appeal
6 - Above average / So-so anime that had "something"
5 - Mediocre / So bad it's good.
4 - Bad shows / Not for me and should've dropped.
3 to 1 - Waste of time. I very rarely waste my time.
I have many dropped shows. Main reason being that I wasn't part of the target audience and would have scored between 1 and 5 if completed. This is also why I rarely score shows lower than a 6. I tend to drop them before finishing them.
Simple policy: Don't like -> don't watch -> don't rate.
Other reasons may be that I read the manga / played the VN / watched part of it on TV during my childhood.
Age 4-7: Maken Liner, Akira, Captain Tsubasa, Saint Seiya. Early 90's.
Age 8-11: Saint Seiya, Sailor Moon, Sakura Card Captor, Speed Racer, G-Force (Gatchaman).
Age 12-15: Slayers, Evangelion, Dragon Ball Z and pretty much everything aired by Locomotion (Wikipedia Link).
Age 16-18: Broadband Internet Stage: Romance anime on Crunchyroll: Kanon06, Air, Haruhi; also new-gen shonen: Naruto, Bleach; and loads of Manga and some popular VN (F/SN).
Age 19-Today: Consumed massive amounts of anime/manga/VNs. Following currently airing shows.