1. Charlatan - These consultants fix some things, but often implement changes that have negative results as opposed to the "big gain" that was proposed.  These are the business consultants that spend more of their time in court and in practices to limit their liability in court.  You can find the details of their court cases all over the internet. 
2. Packaged - These consultants have avoided the courts with a 1980's plan of improvement they expect to implement long before they even conduct the survey/analysis.  They offer value, but sell what we call a "packaged" solution as a custom solution.  These solutions attempt to move you 5-10% closer to a 1980's target of  "good".  For many businesses, this is a positive step. 

Unfortunately, these are "high pressure" sales where an analyst on a "FREE FINANCIAL ANALYSIS" suggests the financial sky is falling and lucky for you we have a consultant ready and close.  Be weary of the high pressure sale - they usually improve things, but stay till they get kicked out and the ROI is dismal if it exists at all by the time the business owner wakes up to the fact they aren't leaving - they keep coming up with new projects.

1. Optimization Consultants - These consultants can not only implement/teach a more updated and productive basic business practices, but they also optimize a business.  They use six-sigma, lean, computer modeling, best practices, Monte-Carlo simulations, data analysis, and a whole host of other techniques to find the HIGH RETURN problem and an OPTIMIZED solution.  These solutions offer the potential for 6/8/10+ TIMES the productivity over the packaged solutions.  They offer the best potential for a quick fix of the right problem with big results!