Is there any chance I should implement
those anti design patterns in my
application ?
There is a chance you'll implement various anti-design patterns as you may fall into situations where it appears like, "This looks good let's do that," only to discover later that, "Ah that wasn't so good after all." Will you intentionally knowingly implement an anti-design pattern? That's another story as some people may like learning things the hard way and so to really see the lesson of the anti-pattern they'd implement it and see what happens. Other people may take the cautionary tale and know the lesson without having the direct experience of it.
EDIT
When Jeff said: “A basic rule of programming is to never write what you
can buy or get for free,”.
Which I believe is the way to
implement copy & paste programming
then should I say that SO is ,in some
way or another, following
Anti-Pattern?
No, though there is something to be said for how a lot of things can be misused or abused at times. Consider the basics of a knife. This can be used as a weapon in combat or as a tool to cut food into bite size pieces to make it easier for some people to eat. Should there be no knives in the world simply because they could inflict harm? I'd think not as there are lots of good uses of a knife and so I'd like to see them stay as something I can use with food. SO can have some parts that if taken out of context could be damaging but this is true of a lot of things in the world where a little information can be a dangerous thing.