It depends. A few gimmicks and routines aren't the end of the world. I know a normal guy who uses them as he finds the funny and actually has an attractive personality to go with it.

The problem is they are often used as a crutch. Like this is all you have to say and the reactions they get define whether the girl likes you or not.

And thats why they shouldn't be used for people trying to learn 'from scratch'.

Rather than being a social, cool, good looking guy who can flirt whilst being normal and a bit of a challenge or at least having a spark.