I think the rule of thumb for choosing a vendor, agency or consultant, is whether or not they will leave you off better than when they found you. And this is not just in terms of increased sales or other KPIs. As they increase sales are they also increasing the competency of your organization so that one day the vendor/agency/consultant will work themselves out of a job?

This is an unselfish stance for a partner to take that requires:

• Transparency. The client needs to see exactly how their partner is doing what they are doing. Too often agencies pull the wool over the eyes and make what they are doing look like magic so that the client feels like they could never leave. Vendors that use superior algorithms as their core competency maintain their clients by selling a threat that if they ever leave they will be worse off.
• Aligned Interests. When the consultant or agency is “open kimono “ it becomes very easy to see if they are on your side or if they want to do just enough to stay employed.
• Constant improvement. Due to transparency and aligned interests, as the client becomes more capable to handle the things the agency was initially hired to do, the agency needs to provide more value and take on other deficiencies that the organization has.

Too many agencies keep their processes secret for fear of losing their job but when the partner has reached a point where their services are no longer needed due to their transparency and aligned interests they can gracefully bow out and send the improved client on their way. Of course any client who has ever hired a partner with this level of commitment is rarely ever let go.