Why the observed black hole candidates do not show spin pulsation
  It is shown here that the so-called spinning Black Hole Candidates (BHCs) cannot be Black Holes (BHs) at all and, on the other hand, must be spinning hot Eternally Collapsing Objects (ECOs). The question would then arise why the spinning BHCs do not reveal their spin pulsation unlike the spinning cold Neutron Stars (NSs). Even for magnetized NSs with ``hard surfaces'', there may be no observed spin pulsation if the dipole axis and spin direction are exactly same. However, spinning ECOs do not show spin pulsation because their surface gravitational red shift is extremely high, z >> 1 and could be in the range of 10^{7-8} for stellar mass range. In contrast NSs have z ~ 0.1 -0.3. The time profile of periodic signals generated on the surface of a spinning MECO get extremely distorted due to extreme general relativistic frame dragging effect as they traverse through extremely steep gravitational field. However, if any radiation would be formed in the ECO magnetosphere sufficiently away from the surface like in the pulsar ``outer slots''(which may happen for isolated spinning ECOs), it might be a pulsed one. 
Abhas Mitra