Rating Systems in Manga

For those of you not familiar with my manga reviews, I do not have a rating system.
Why?
What I've noticed while looking through baka updates and filtering the kind of manga I want to read from the ones I don't, I always take notice of the rating.
If gives me a ballpark idea of whether the manga is good or not.
That is by all means fine and quite useful.
But the problem is a lot of it isn't an accurate reflection of whether it's really good or not.
A lot of the ratings are really subjective.
For eg. there's your stereotypical shoujo oneshot.
For an avid shoujo manga freak like me, I always judge things based on the purpose of the manga. Most of them are just fluff to read to kill time so I would probably rate it, say a 7.5.
On the other hand, if someone was actually judging it, having only read really meaningful stories then they would probably give it a 4.

Same scenario can be used it there is a deeply emotionally driven plot.
Someone like me would rate it a 9 but someone who loves cheesy crap mixed to together with comedy and hot bishies might not appreciate it so much and give it a 7, labeling it boring.

Rating systems only work if you have certain standardized criteria. That's why I don't have such rating systems because dissecting a story and slapping on a number isn't how I feel it's supposed to be seen. Sure you break it down into simpler parts but logic, reasoning and numbers isn't supposed to be associated with manga, especially shoujo.
Your supposed to review it as a whole (how well it's put together), the purpose and it's intended audience.

Some are obviously better in the morals, execution and art. I feel like putting rating systems for those wouldn't be bad.

Well done with this boring post. Look forward to more reviews...