Idioms: good stylistic effect or not?

I try to use them on the forums because if I don't use them i tend to forget them. I wouldn't normally be holding a conversation using a lot of idioms, I wouldn't definitely like to put the other person off. But I would be inclined to think that native speakers use them now and again. I would say it would be more useful simply to recognise them.

hey no doubt idoms sound stylish, but i think you should do some reserach on where exactly to use them and where not, for eg. in my early days i used a few of them in some letters and my teacher was mad at me, but at times they do add spice to your articles.
btw any good site suggestions for idioms ?

Idioms are not always informal. There are formal idioms as well, and they are appropriate to formal situations, just as informal ones are appropriate to informal situations.
Idioms are fabulous. Because idioms, slang, sayings, etc. have a narrower range of connotations than most words, they can add a lot of colour to your writing when employed well.

And yeah. It's kind of silly to ask whether something is a good stylistic effect, because, well, pretty much anything can be stylistically useful if you know how to use it. The problem comes when these things are used poorly.
For that reason, it's dangerous to use colloquialisms. Unless you are very familiar with how an idiom is used, I would recommend avoiding it.

But why is it that those so-called teachers of mine gets all gritty when they see idioms and metaphors. Teachers loved those in high school. Oh well, I'll wait 'til I become the teacher, hopefully, and have my revenge on my students lol j/k

Possibly you are using them inappropriately. But I couldn't say for sure without seeing specific examples.

I guess I should just listened to my current teacher, besides, my teacher now is the judge of the current state of my writing. So far, I haven't had problems with my first college English teacher because I didn't feel using idioms during that time. The only teachers I'd have problems with were people who think they are teachers and stuff (I guess, I shouldn't have used the word so-called e

Actually, "so-called" generally means that they are not what they seem. They are called teachers, but in your opinion are not actually. The expression is generally used derisively rather than literally.

Actually, I meant they were not really teachers, but they view themselves as teachers, by the way they act and stuff.

you are write t, every site suggests idioms.