http://www.sequoiacap.com/ideas/
(Currently down, Google cache below)
I really like the Sequoia list -- perhaps because it's like a point you can look at and aim for when trying to sort out business ideas.
# Initially sells to the enterprise for branding, credibility, awareness and early revenues
# Can get to revenues within 6 months, tops
# Is sold on the basis of ROI, e.g., helps generate revenues or reduce headcount/costs
# Integrates easily with existing platforms and/or programs
# Either leverages existing open source programs or can itself become partially or fully open source
# Has multiple revenue streams, e.g., software, maintenance, services, etc.
That's all describing a particular kind of business. It actually seems like it's describing a reasonable sepcific area: tech/service hybrid focusing on large-ish b2b clients.
I think the main problem here is that I see problems and I immediately want to solve them. The goal for an investor is not to find and solve good problems but to bet on good teams. As Josh Kopelman says, it's about the chef, not the ingredients.
So mostly you end up saying "no" a whole lot. If you give an explanation as to why you don't like it, many entrepreneurs will simply change the details and then expect money, so you can't even generally give a reason. I think I spoke to north of 90 companies to consider even the eight deals I have done. Between that and incoherent summaries, MBAs with just a powerpoint deck, etc, I just get too tired.
If the signs are this obvious then the valuation would already be high enough to be unattractive to an angel.
I've done some (roughly 8 deals) angel investing myself, and prefer to look for something market-shaped; matching buyers to sellers, or similar; a team I would seriously consider working for; and a working prototype for me to look at.
The first is because that's the kind of thing I like to think about and because I think those tend to be scaleable businesses, the second is because as an angel I want to actually spend time for them, and the third because I think most powerpoint presentations are crap.
There are some additional parameters around investing (like how much the valuation is) but I'd much rather help an entrepreneur who is going to shoot for the moon.