Dunno...
But you go thru most threads on the forum and heaps will say something along the lines of the cheapest rate isnt the best product for what you want.
What I think your question is revolving around moreso is getting stuck with a 600 bill if you dont proceed with the broker. I fully enforce my clauses as long as we get to unconditional but that is more because we're running a business - we spend time on the road, processing the application, making sure its all lined up, organising valuers, settlements, solicitors, insurances, arguing with a mortgage insurer because a client had a default which nobody knew about or finding a lender who will accept a clients numerous defaults etc etc.
This is inbetween keeping clients in the loop, chasing up the banks etc... the list doesnt end ever really. So as a broker we're still running a business, so we have fuel costs, internet, public liability insurances, storage fees, office space - same expenses as any other business, plus bills to pay of our own
So to do all of the work for free and then get told 'too bad' at the end can mean (not that it happens heaps) and you're out of pocket for what - easily 15 hours work. Find me anyone who works for free for 15 hours. If they do then I'm happy to get them over to my building so I can save $32k on painting it.
Then have the possibility where the clients really shopping you on rate and a few months later they refinance and all the money the lender pays out gets taken back and the broker then suffers a loss well and truly.
IMO - forget that - I'm not in business to just drive around and give advice and do work for nothing in return.
But I also find it weeds out the bullshi* artists or people who arent being totally upfront with us - and those are the clients I (and I suspect most brokers) really dont want anyway.