Why shouldn't I use duct tape for home improvement?
Yes this question should be closed, but in the meantime, the quite-serious answer is:  don't use Duc[k][t] tape for anything. Ever.  It's only partially a joke that the only thing duck tape sticks to is itself.  It ages very fast, with the cloth backing falling off and only a difficult-to-remove dried layer of goo remaining on whatever you thought was being held together.

Basically, duck tape is useful for very short-term emergency use only.

(For those who care, the original name was "duck," not "duct," as it was named for the class of sailcloth used to manufacture the tape.)

Edit:  Johnson&amp;Johnson's own history page says the original duck tape used duck cloth.