The print become impossible to remove from the bed, and you eventually break the piece...
Well, I found a very cheap and easy solution to fix this problem: Acetone substitute made out of 2-butoxyethanol (like this one: http://goo.gl/gnF4Yv)
It is not only cheap it is also environmental friendly.
It does not make the ABS sticky so you cannot use it to smooth your print, but to cleanup the ABS juice or to remove the print from the bed, it only takes 10 seconds and few drops.
If you leave the piece in this substitute for a long period, ABS will become like chewing gum but still wont be sticky.
I bought it by mistake, but it is not my best friend. I can put as much ABS juice as I want, my print will always detach perfectly.