They not only provide financial support but much needed mentoring and coaching. They also take more risks. Other than doing some background and reference checks, they rely on their instincts. And they do deals quickly. If they don't like a deal, they won't string you along by asking for a business plan or more details.
Angels generally prefer to maintain a low profile and they enjoy their privacy.
Good entrepreneurs are good networkers. They know how to find prospects in a crowd. Upon finding a supporter to advance his cause, the entrepreneur will get fifteen minutes or so to make a pitch to the network. If little or no interest is garnered, it is a sign that something is wrong. Pitching the same proposal to more investors will likely produce a similar result.