My experience is that it depends on the type of encryption used. For the "official" high end formats available to all radios systems, such as AES, the scanner "skips". You may briefly see "ENC" on the display.
For the "budget" type, such as ADP, which started out as a Motorola propietary deal, you may hear an awful and broken racket. Sometimes you see ENC and sometimes the scanner holds on the channel, perhaps just briefly.