I have started reading 'Rice, Rivalry and Politics', a book about the international relief effort in Cambodia after the fall of the Khmer Rouge and the situation seemed extremely shocking to me. In the book, the authors talk about the political situation on the ground, and how aid effort were made difficult by many different factors. The most shocking factor for me was that the Heng Samrin government was struggling to find enough people who knew how to count to assist in distributing the aid! Was the international aid response in Cambodia as terrible as the book claims?
To be honest I had never heard of this book, but I had a look at some reviews on Jstor and it seems fairly well received. So with out having read the book myself I can't comment too much on it's content. If the two authors were on the Thai border helping with the aid program there then they would have been witness to just one side of the effects that the realpolitik of ASEAN, China and the US policy was having. That is to say that they were not in Cambodia itself, which was receiving next to no international aid.
The astonishing way that aid was distributed by the US and in the same way, how aid agencies were forced to supply this aid predominantly to the broken Khmer Rouge forces that had retreated from the country -- as well as to the 300,000 or so refugees on the thai border... is one of the most disappointingly cynical aspects of the whole mess in Cambodia, considering the 6,000,000 people still in the country that were in an extremely dire situation.
As reading the book has no doubt pointed out, that 'rivalry and politics' part of the scenario did a lot to hamper the recovery of the country after the calamity of the regime and the war with the Vietnamese.
The aspect that you bring up, about not having enough people that could count, that does sound anecdotal and I wonder how it is presented in the text? Like did the author's hear that? It seems like it could be a hyperbolic reference to the persecution of the intellectual classes, which makes sense... but whether it is exactly true I would think a little far-fetched.
But, just to circle back to your question, yes the response was 'terrible', but it was hampered by the cold war rivalries that the whole mess had started from.