So it is purest slander to say that ALF is “an organisation willing to send bombs to maim or kill”.

No the question is whether using rape for law enforcement is acceptable.

Yes I would consider intentionally using this sort of tactic to be a sort of rape.

That’s yet another question.
Even if the police officers had infiltrated the ALF, which was willing to commit murder, without becoming sexually involved, was it the only way to catch them and would it still have been justified? In Lambert’s case, he seems to have used a woman completely outside the ALF and arranged for her to be raided by the police to boost his credentials, which even supporters of the policy regard with distaste- would he have been justified in seducing an activist who was willing to kill?
Female police officers also became sexually involved with activists- were they rapists too? If twoundercover officers seduce eachother, is it rape or incompetence? If a police officer seduces an activist out of pure lust, rather to infiltrate the organisation, is that rape? There are an enormous number of questions to be looked at, even if you accept the doctrine of the lesser evil. The noteworthy thing here is that this tactic was used against completely legal and law-abiding activists. Even if it could be justified in the case of people like the ALF, it seems to have become accepted as a general tactic remarkably easily.

In the case of the ALF at least, they dealt with an organisation willing to send bombs to maim or kill. Whether infiltration was the only way to deal with it is another question.

No the question is whether using rape for law enforcement is acceptable.

Yes I would consider intentionally using this sort of tactic to be a sort of rape.

Or got romantically compromised ie. fell for their targets much like the girl in Le Carre’s Little Drummer Girl novel did and turned into *double* double agents secretly helping or tipping off their targets?

Also what good / harm did it cause? Any evidence or cases where this actually prevented any attack or instigated one or came up with anything useful as far as fighting crime goes?

I can certainly understand trying togatehr intelligence on secret eterroirts cells even wanna be anarchist / racist /jihadist ones but open public protest groups using non-violence and committing no crimes worse than trespass and maybe vandalism – seems a bit like overkill. So to speak!

Why does the infiltration of peaceable protest groups seem to be just accepted as normal?

It wasn’t the original intention, I think, but came about by default and was regarded as an acceptable activity later. One of the most infamous police agents, Bob Lambert, successfully infiltratred the Animal Liberation Front, who carried out arson and bombings, but he went through several organisations to get there and seduced uninvolved women.
Perhaps we ought to consult Jesse Berings (see Pahryngula} for this.