When I did backgrounds, the first page I would skip to was the previous agencies you applied to and did not get hired by. I could call my buddies at whatever agency, send over your release, and find out why they disqualified you. Then I'd qualify that information and it was usually a quick axe to the file.
We were very picky, not saying every agency is like that. But when we got applicant who provided a spreadsheet of 45 agencies they've applied to it's a red flag. Polygraphs are double-edge swords. Tell a lie, get denied. Tell the truth, get denied. That whole "character" thing has different meanings at different agencies. Some look beyond the past, others hold it over your head forever. Tried smoking weed at 17 and you're 30 now? I knew a deputy chief who wouldn't touch that applicant. Other agencies just have a 1 year separation from use.
Keep shopping, you'll find something. Also, have a meeting and review your background packet with your BI at the beginning. Some agencies do it all and bring you in for your poly as the final step, which leaves very little explanation on the applicant's behalf.