All contractors are same, these ppl try to con something out of their cients. So as a client, we have to be alert and able to control the entire situation of reno works.
I using the same contractors with my wife sisters, but I heard she had big argument and complaint abt the contractor. But, I don't have such big issue with the same contractor which only minor matter which I still can absorb. At final day handover key, the contractor boss himself help me clean and wash the entire carporch and till now he haven't collect his final settlement from me..

Also, he is the among cheapest of all contractors. The cheap means bangla price also no near to compete. However, I still deal with him all with black and white especially those progreesive claim..

Contractors are prone to find loop holes of the job scope, if we as client clear with our job scope and these contractors has no chance to make out of these loop holes job scope, hence they will do the job accordingly.
As a client, if we able and know-how to handle them, I believe issue will be minimize.

I told my contractor: whatever things that I had obstructed u not to do, pls do listen to me. I do not sound out does not mean I can't see.

Fyi, a bangla quoted me before with verbally only. Howeve I pursued him that I need written quote, he indeed did so and write in a letter all scope and of course not glamour english but I able to read with his signature. Later he pass some leaflet of his services to my letter box..

My plaster ceiling contractor don't know english, but I also not know chinese, hence indeed he draw the picture for all scope of work with signature.

To my wet work contractors, he only a secondary graduate which don't know english and write any receipts, hence I prepared the receipts and he sign..

In short, we as client must be control and don't follow their way.

Just my opinion and the way I deal with contractors.