This comment thread in particular may provide more information about your challenge in finding monetary success than your entire wonderfully written blog post.
Here, in quick succession you first suggest that you have very little ability to change the UI because you are a bad developer, then quickly follow that up with a confession to somebody who wants to give you money, that you've made it annoying to contact you because you don't want spam.
I'm trying to be helpful here, not trying to be an a$$, and I understand that you're frustrated with your current situation with Twicsy and your generally long-challenging experiences making a mint with your startups.
However, take a deep breath and realise you've done 3 times what so many have failed to do even once. You've launched 3 products which have seen some manner of success, two raised rounds of financing, and the other has a good volume of traffic. Give yourself a bit of credit on the positive.
Now the negative.
It is said time and time again, execution is everything. You should know that. I just took a look at Twicsy, and honestly the design isn't that bad, but it could use a touch up. If you aren't good at 'web development', get somebody to help you. I'm sure you can find a local developer who would like to have twicsy on their portfolio, or spend a few bucks and get it done.
Secondly, make it easy for people to advertise on the site. If you are going through an ad network, you're not doing the work anyway or put up a contact form on the site, or even put your e-mail in your HN profile. You want to be a success, ABC/S/whatever. You're missing opportunities where people want to give you money, and if you're missing those opportunities, I assume you're also missing opportunities to sell.
The 'build it and the money will come rolling in' days are long gone. Nobody is an overnight success, particularly those that make it look easiest. If you want success, you'll have to work for it. Or else, you'll have to settle for telling everybody about your 'almost successes'.
As I said, I hope this isn't coming across poorly, as I'm truly trying to help you, this thread just made me make a bunch of assumptions about you, and if I'm right, hopefully it will help you or somebody else.
You've struck a nerve with me here, which is why my writing may have a tinge of hostility, but maybe a small crack of the whip will wake you up to your current opportunities and how you can seize them.
All the best.