What can go in a purchase contract and what cannot?

A lender friend, Jeremiah Arn from First Place Bank, sent this:

What’s up with Realtors who want to put a $1,000 seller credit on the HUD for (something ridiculous)!?! I have a deal right now and (an) agent is ready to lose the deal rather than give up . . . (the ridiculous thing). Do they think we give loans for (something ridiculous), or painting, or appliances, or cars, or trailers, or….? I can understand wanting to have that in a contract because transactions outside closing or under the table aren’t enforcable. But if you want market rates (by securing a Fannie Mae-salable loan) you have to play by the rules. . . .

It can be surprising to find the vast array of things that find their way to the purchase contract. If it's in writing, has signatures and deadlines and specifics, then itenforceableble. But lenders don't want financidecisionsons about home decor, landscaping, and credits for this and credits for that taking up space on the final HUD statement. They are concerned with details of the property transaction and the fees associated with the lender and title companies. The buyer and seller want a nice clean final statement too -- it benefits everyone.

I'll try to get some definitive statement from a title company representative on what can and what cannot appear on a final statement.