With respect, my friend, this is exactly the process which I consider unethical.
Well, I may not be your friend for much longer if you think that .
Look Tracey, I understand your position, I just happen to disagree with it. The vendor is under no compulsion to renegotiate anything after an attempt by me to have a price reduction or have a fix made at their own expense. They can say 'no' if they so choose. Then it is up to me as to whether or not I want to proceed to exchange.
The reason we hire a building and pest inspector (most times) is that we are not experts in that field. We would have made an offer based on what we see through our own eyes and forming an opinion on the property's worth to us. If an expert comes along and opens our eyes to problems we did not know existed, then in my view, the property just went down in its worth to me....and my attempted reduction in the price I'm prepared to pay, will reflect that.
I am very one-eyed in this process I agree - one of the job hazards of being a BA and NEVER (hopefully) being a vendor.