Insurance is the number one reason, and it's almost always a paperwork mismatch rather than an actual coverage problem. Google needs your certificate of insurance to show the exact business name that's on your LSA account. If your policy says "John Smith" and your account says "John Smith Painting LLC," that's enough to trigger a rejection. Get your agent to reissue the certificate with the name matching exactly.
The second big one is the license question. Painting is tricky because licensing requirements vary wildly by state. Some states have no painting-specific license requirement at all, which confuses the system. Google still wants something, so if your state doesn't license painters specifically, you usually need to submit a general contractor license or a business registration document. A lot of companies get rejected simply because they don't know what to submit and leave that field incomplete.
Workers' comp comes up a lot too. If you have any employees at all, even part-time, Google expects to see workers' comp coverage. If you're a sole operator with no employees you can usually claim the exemption, but you have to actually submit documentation for it. Leaving it blank reads as non-compliant.
Background check failures happen more than people expect, and it's often the verification service not being able to confirm the owner's identity because the address on file doesn't match public records, or the name is slightly different from official documents.
The fix in almost every case is getting your documents to match each other perfectly before you submit, not after the rejection.