I have been in the IT field for over 25 years, and it is pretty common to be approached by consultants from every possible area.
Social media has made it even more predominant. I came across this referenced article, and I couldn't help but share it since it really hit the mark. I have also entertained the possibility of having a consultant put another set of eyes on infrastructure challenges and strategies. However, I often find that what looks good on the surface is just bait to sell or steer me to products that they are obviously benefiting from, via profit sharing or commission programs, with vendors whose products they push.
The bias of this practice in all fields is something everyone should be made aware of. When it does occur, the consultant has, in essence, lost their sense of being unbiased and their sense of what is good for the customer. This article speaks to IT, but it has application to any industry. It does a great job of highlighting areas you should look for and ask questions to. A consultant should have your best interest and the success of your company as their primary focus. They should focus on their core competencies and not how they can add to their profit bottom line.