Step 1) Ask them "what terms are you ranked for?"
Step 2) Listen to them make excuses about why they are not ranked even though the call themselves SEO experts.
Step 3) Cross them off the list.
The SEO consultant you work with better show you they are good enough to rank themselves. Otherwise they are selling snake oil.
If it helps-- we are ranked for some of the most competitive terms out there. Feel free to shoot me a call request if you'd like to actually RANK your site instead of pour money into it for months only to find out google has penalized you.