I had an 01 for 3 years. No inspections. Had 07/02 for 5 years now. No inspections. No traces, and anything I sell locally is extremely unlikely to be traced. Stuff I sell online = who knows?
When you renew your license, they want to know how many acquisitions & dispositions in the last 3 years, so I suppose they use that data to get an idea of how much stuff you're moving. I do about 30-35 4473s per year, and I'm way out in the woods, hours from any office, so I imagine I'm a low priority. I think the inspection frequency varies a lot, depending on that licensee's data.
I try hard to stay on my toes and be ready for it when it comes, though.
When it's low volume and one person handling all the 4473s, much less likely for a mistake than an employee in a busy store.