We've played "rescue" to 3 so-called approved loans with an un-named biggest box bank this past week. All 3 were given pre-approvals to go find the home of their dreams, only to be told later they didn't qualify.
With everyone's terminology being different, I would put the burden on the listing agent to call and quiz each loan officer with a letter accompanying an offer. Ask them exactly the concerns you mention: did they verify the income (and how), do the assets exist (in place or liquidation required), are the scores acceptable for the loan program and other than the appraisal are there any other issues? And when they say yes, all is good, say great, send me an email or fax to that effect, or you can't recommend the contract to the seller.
I don't think some still get it. People are making life decisions based on these letters, incurring in some cases, thousands of dollars in expenses. "Ooops, I missed that" just doesn't cut it. The changing guidelines are hard enough as it is, but add to the equation someone that isn't taking care of the bare basics, well, they need to be weeded out.
It's all about expectations. If agents prepare sellers for the screening process and requiring a higher standard, you would think buyers and their agents would get the message when their contracts are not accepted, or even presented. Interviewing the loan officers is legal - you are not asking for confidential information to exchange hands. An argument could be made for borrower's expectation of privacy, which could easily be combatted with a release to disclose the peripheral data, but no explicit information need be revealed. (Most new construction contracts already contain such language to disclose to the seller).
It got so bad in our area, there was one particular outfit in town......no contracts were accepted if the letters were written by them. We are back to the offers with escalation clauses or multiple offers. I have advised my buyers to take their credit score disclosure notices and attach it to my letter (they have to do that, not me). In some cases, I have told buyers to attach a redacted bank statement or even W2, if the competition was tough. If your market is slow......it's even more important not to lose time off the market.