So, I talked with folks who work/worked with other agencies, and I'll say this. I believe the CPB agents see whatever is in NCIC. So, don't think you'll get anything by them...if it is still in NCIC. There are also off-line, deeper searches. You can google off-line searches, and you'll see those searches do not occur nearly as often as people applying for GE. Off-line searches not only tell you the history, they also tell you who has pulled the record, when, etc. I believe the government publishes they do 22k off-line searches per year (much less than GE applicants). That is public record or at least stated to the public. If a record is expunged correctly as stated by many in this thread, at the federal level, it would not show up on a normal NCIC criminal history search. This is as I thought. I seem to recall people who had felony arrests that were blank on their criminal history after correct expungements. I just didn't see a before picture to tell if anything was ever there in the first place, but it had to be. This was probably 10 years ago that I recall, but I wouldn't think it's much different.
If you were applying for a job with CPB, they would likely do a formal background investigation, which is much different than a simple NCIC search. That's boots on the ground knocking on your neighbor's door. I don't know what advice to give to someone from there because you can't truly look into NCIC by yourself. Criminal histories are a guarded section of NCIC, even to a local LEO. They need to get them, however, sometimes to do their job. For example, when you need to verify if someone is a convicted felon, or has a domestic violence conviction, and is carrying a handgun, you may need to run their CH. You will also document who requested it. This also ensures no friends of friends can get their buddies to see the CH of who their daughter's dating, etc.
On another note, the CPB agent didn't ask questions about arrests or convictions when I applied for GE. They certainly would if there was something there, but that at least adds a DP that they aren't all out to see what kind of dirt they can dig on you even if they get a blank screen. The agent didn't really hide the monitor on us either. She actually was pointing to the screen as she noted everywhere my prints have been run for security clearances.
I think people are making more out of this than it is. If someone has a legal binding document (signed by a judge in that jurisdiction), they should have the right to do whatever the document says they can do. Then, if anything is odd, they can then explain in detail why something is in NCIC. Again, this is just my opinion. At the end of the day, I do believe it's all about what is in the federal criminal history record that is accessible to all LEO agencies. I have no idea what websites pull, but I would trust NCIC over them. I'm NOT saying go beg your LEO buddy to come up with a reason to run your CH, but I do believe it's all about what's in NCIC. If for whatever reason, good or bad, you have an opportunity to look at what prints out of your CH, that should be the info you need.