Sounds like you've had a bad experience, and I feel for you. To provide a bit of a contrast, I currently work with a consultant who I am extremely happy with. I think it helped that I had clearly delineated goals that I knew a consultant could help with, and knew what parts of my application I was confident I could perfect myself (editing, grammar, and style being an example of the latter). Each person has a different experience, and I definitely agree that people should do their due diligence and actually talk to the person they'll be working with (though asking to see other people's materials is probably not going to fly for confidentiality reasons). My cycle has been going great—no rejections/WLs so far, multiple T-14 acceptances—and I know my application would've been worse without the consultant's guidance.