edit: This must be misunderstood. My intent was to illustrate that Twitter is not a good example of a company that has been acquired without a solid business model. Obviously the news says they've had offers, but just as obviously no offers have turned into acquisitions. The many intelligent people who work there and have invested in the company think Twitter has at least the promise of a solid business.
Regarding your edit, you said it yourself. Here's a company that has had multiple acquisition offers, a company which people would consider a bargain at a billion, and the best it can do towards a business model is "at least have the promise of a solid business".
If I had a business that generated even 30k/yr in revenue (albeit a sustainable 30k), I would think really hard before selling it. It pays my living expenses, after all, and ostensibly leaves me free enough to pursue other ideas.
This "acquisition fever" we have these days isn't really about good business models, there are the businesses which try to grow as fast as possible by burning investor money and disregarding business models (the ones that are good acquisition targets), and the businesses that start out with a good business model and aim to be sustainable as fast as possible.
edit: This must be misunderstood. My intent was to illustrate that Twitter is not a good example of a company that has been acquired without a solid business model. Obviously the news says they've had offers, but just as obviously no offers have turned into acquisitions. The many intelligent people who work there and have invested in the company think Twitter has at least the promise of a solid business.