Just to be very clear, the passive PoE solutions will not attempt to detect a supported device, they just supply a constant voltage. But there are few switches of this type, more common with inline power injectors.
(Also people using passive PoE in their products ought be taken out back and, uhm, be dealt with)
((compliant devices will also have just the PoE PD circuitry powered until handshaking is complete and the host device receives power))