There's little rejection in left wing parties and German trade unions (with the exception of the police unions, obviously) with regards to ACAB and similar messages, although you won't find anybody running for chancellor embracing it. As they will march with the Black Bloc on ocassion, I don't think you can draw a clear line.

The parties' youth organizations are generally significantly further left, so that's a different story entirely, but that's probably true for any youth organization.