I've been driving a 2015 RAV4 regularly for the past 6 years.  I can't really say much about what to look for with the car, since I haven't had any problems with it.  The only annoying thing is how slow the automatic rear hatch opens and closes.  Other than that, amazing vehicle.  

If you are checking it out yourself, just the common things, do they have a service history? How many scratches or dings can you deduct from the price? Has service been done recently? What is the condition of the tires? Does the interior smell for any reason? Do the fluids look clean or good enough? Is anything broken that you can see off the bat? And or if you are lazy to look up a tutorial for this then see if you can get him to let you take the car to a mechanic. If they don't allow it for whatever reason it is not the one to buy. As most people who don't allow a mechanic to inspect the car are more than likely hiding a thing.

They are good cars, make sure to have a mechanic check it out. Look over service records if you can, and make sure the transmission fluid was changed <60k miles, if not they tend to have problems.