Correct. A dealer's license is a business license and BATF has the authority to inspect a dealer's books and premises at any time during business hours. A collector's license is just that, and a collector is assumed not to be in business (in fact it is illegal for a collector to engage in the business of buying and selling guns) but to be a private individual who engages in collecting activities at his home.
In fact, I have known C&R license holders who have never had any BATF check in years of having the license. The only way a collector can get in trouble (if state and local law is obeyed) is for a gun delivered by him to turn up in the hands of a non-collector after an illegal transfer. A collector can sell to a non-collector but only as an individual, not under a C&R license - that is engaging in business.
Jim