All major Python implementation have a mutual agreement that callable() just checks for a __call__ member on the type. You also haven't shown that this behavior violates the documentation and language spec. The check for existence of __call__ on the type is well in the range of expected behavior. I as well as other core devs had the same gut feeling.

Finally your suggestion makes the implementation of callable() more complex and much, much slower. Right now and for more than a decade it is a simple, fast and straight forward code path for new style classes. It just requires two pointer derefs and one comparison to NULL. I'm still -1 on the change.

If you want to go forth with your request then you must write a PEP and convince all implementors of Python implementations to change the current way callable() and other protocols like iter work.

$ python2.7
Python 2.7.8 (default, Nov 10 2014, 08:19:18) 
[GCC 4.9.2 20141101 (Red Hat 4.9.2-1)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> class A(object):
...     @property
...     def __call__(self):
...         raise AttributeError
... 
>>> a = A()
>>> print(callable(a))
True
>>> a()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in __call__
AttributeError

$ jython 
Jython 2.7b3+ (, Nov 3 2014, 11:02:14) 
[OpenJDK 64-Bit Server VM (Oracle Corporation)] on java1.8.0_40
Type "help", "copyright", "credits" or "license" for more information.
>>> class A(object):
...     @property
...     def __call__(self):
...         raise AttributeError
... 
>>> a = A()
>>> print(callable(a))
True
>>> a()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in __call__
AttributeError

$ pypy
Python 2.7.8 (a980ebb26592ed26706cd33a4e05eb45b5d3ea09, Sep 24 2014, 07:41:52)
[PyPy 2.4.0 with GCC 4.9.1 20140912 (Red Hat 4.9.1-9)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>> class A(object):
....     @property
....     def __call__(self):
....         raise AttributeError
.... 
>>>> a = A()
>>>> print(callable(a))
True
>>>> a()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in __call__
AttributeError