Some home inspectors may fear if they speak too openly about the flaws in a home they will anger the realtor and never get another referral. It is necessary to work WITH both groups. A good inspector will never work FOR either.
Most inspectors do however market to agents in some form because they can provide referrals.
The worse agents try to find new inspectors who are still green and naive to the agent's possible tricks. This is not to say that they do poor inspections, but that their alliances may not be independent of the needs of the client, who should never be the real estate agent. This is an area that might be a signal of a poor judgment. A few inspectors have bragged about their newly created income by being the agent's best ally. This is not the kind of inspector you need to give an unbiased viewpoint.