References are crazy. There's no simple guideline to use them safely. Check this out:

    const string& s = max<string>("a", "b");
    cout << s;

Standard types and functions, const references, no warnings, everything by the book. But it crashes.

There's a similar can of worms related to slicing (treating Derived* as Base* is silently unsafe because arrays and copy constructors exist). C++ is scary.