Good question Bryan.
I didn't mention anything about tax returns or reserves more because those are a given these days. The reserve requirement can vary widely from lender to lender, but as rule, you should plan on having at least 6 months of PITI above and beyond the down payment. That doesn't mean you need cash sitting in a bank. 401k, stocks, mutual funds, or any asset that can be liquidated would generally suffice.
Given most commercial loans are full-recourse these days, it doesn't do the lender much good to have the borrower guarantee a loan if that guarantee is worthless. Having good credit, reserves, and experience, are the foundation a full-recourse loan.
Since these are small balance commercial loans, the borrower's credit score is also a consideration. I can't tell you what score would be a deal killer, but I consider anything below a 680 a possible issue.
NOW, that being said, there are some lenders out there who will underwrite the property more heavily than the borrower or vice verso. I have one lender who doesn't even appraise the property on small balance commercial loans. It sounds odd, because it is, but that's the way the do things.