Can’t say I disagree. The majority that I’ve encountered have little to no technical knowledge, even broadly, about the areas they are recruiting for, and rely on downright dishonest tactics. In this country at least, no qualification is required, which attracts a particular demographic.
If you must deal with the agents, question everything they say. However nice they may seem remember they are not incentivised to act honestly. They’re not your friend. Get promises (and the job description) in writing. Check directly with clients whether the agent represents them. Before you’ve signed anything compare notes with the client to find out what the agent’s rate really is; often they’ll lie to you both to gouge out a larger cut. When you catch one behaving deceitfully publicise it so others will be wary. Reach out to the client (pro tip: go straight to HR) to tell them what’s going on. Odds are they’ll be appalled at how they’ve been represented. Have an expert read your contract (most recruiters are clueless about contract law) and question every onerous term. Walk away if they make excuses for not negotiating. If you’re a contractor and at the last moment they demand to see your ID (passport, driving license) refuse; they have no right to it.