I make a living as a trade contractor; and if it weren't for the complaints and bad experiences that people have about other contractors, it would be a lot more challenging to secure long term relationships within which our company can provide reliable and profitable services.
That said, as an investor, instead of asking, "What are your biggest complaints?", I would flip the question and ask, "What are the top three things you look for in a contractor?". So... I guess I'll start that thread in the forum.
Remember, there are two sides in every relationship. We look for long term trade partners that can count on us and upon whom we can depend. The use of leverage is the last resort, and indicates a break down in goodwill and function in the relationship. Treat contractors with respect and honor your commitments. If your contractor needs money down to start a project, then they haven't been in business long enough to establish working capital. If they DON'T need money to start a project, then I'd be willing to give them money up front. (It's like when an investor goes to the bank: The more you NEED money, the less they will give you because they assume more risk). If the contractor doesn't have a track record in your market, then trust them with small stuff. As you grow, they grow. Don't drop them for the cheaper contractor after they've proven themselves (It's likely that the cheaper guy isn't running the business well and is just chasing cashflow, short term win for you, but you'll probably end up with more complaints to add to this list). Appreciate that there is a cost to running a business that can provide solid service in a timely manner... speed of transaction in a flip or renovation saves you money, and everyone wins. Now I'm rambling... I love this topic.