I mean constructors. It's the exception to have to do anything meaningful in the body of a constructor in modern C++ - you can do a lot with member initialisation lists, delegated constructors and defaulted/deleted constructors (remember boost::noncopyable?). And your assignment operators will actually be exception safe.
Constructors induced exceptions, and once we have exceptions they became the failure reporting mechanism of the standard library, leaving us with goto-some-other-function-using-dynamic-scope as one of the foundation blocks of the language. Thus constructors are a reasonable contender for the worst design mistake in C++.
That doesn't even make sense. Maybe you meant "destructors" but even then it has nothing to do with reality