Mary,
Your observation of some "experienced" salespeople is quite astute. I love when they follow me around and huff and puff while I write repairs. Then they get the VC sheet and call complaining that in their 25 years they have never had to do this or that. That's to put you, the appraiser, on the defense. I always respond with, "Oh, this must be your first FHA deal in 25 years otherwise.... you must be lying to me. Which is it?" I just love putting them back on the defense.
But we want to avoid this problem altogether so we don't have to face disgruntled salespeople, LO's, etc who rant and rave and waste our time. Here's what I do. Regarding your question, I've learned this in all the years I've been doing FHA's. When you write the VC sheet repairs, write them to your advantage. Don't say "Repair broken window glass in the front living room window" They will take advantage of you as they have just done and install plexiglass. Now YOU have to second guess their repair and try to require another repair after the fact which is very hard to do. Give them no leeway upfront. State "Install a new glass pane in the broken front living room window" Spell it out exactly so you can shove it in their face when they can't follow what's written on the VC Sheet. I hate using the word repair anything because they will do it as cheap and as shoddy as possible. The word is "install XX" and it better be installed when I get there.
As far as missing or not completing repairs, that's the favorite broker trick to get the appraiser to overlook unfinished repair items. They order the repair insection the day prior to closing. You know the excuses offered, the buyer is ready to close tomorrow, he's packed and has nowhere to go, his rate lock expires, etc. AND finally, You, Mr/MS Appraiser are going to kill the deal. Take care of it by writing on the Homebuyer Summary "Buyer and seller to be given a copy of Page Four of the VC Sheet which lists all required repairs and certifications required." I list all repairs and certifications in detail on Page 4 of the VC Sheet and state that "Incomplete or overlooked repairs found at re-inspection may delay closing." In that way, everyone knows upfront what is expected and if you don't do what is expected what the consequence will be--you don't close. It's then not my fault, the LO's fault or the DEU's fault. It's the seller's or listing broker's fault. Believe me, the DEU will appreciate it if you spell everything out exactly. In your present case, the DEU is not going to take great joy in mediating repair requirements. Also, have the lender fax back the VC Sheet Page 4 to you before you go out on the repair inspection just in case the DEU has added or modified anything you have required. They have that power and I've seen it done.
Don't ever let them make you feel nervous or unsure about a repair in the future. As I said, tell them what you want/expect exactly on the VC sheet. Give them no quarter.
As far as your existing problem, think safety. Will the 3x4 sheet of plexiglass flex enough to blow-in during a high wind. Probably. Is it typically used in a window that large. No.
Ben