A good rule of thumb that I've seen be very effective in the "how to decipher mixed signals" arena is that 3 "maybe/but"'s equal a straight out no. It's just a rule of thumb, and bad coincidence can really screw it up, but if you put yourself forward 3 times and they sidestep it 3 times for whatever reasons, then you can be assured that your interest is known and they will pursue it themselves if it's just a matter of horrible timing.
Anyone who does not pursue after 3 sidesteps by purpose or happenstance is simply not interested.
People who are not interested will rarely change their mind. In my experience, it's best if they don't change their mind, too. As interesting as the attraction might have been, initial guesses at compatibility were generally more correct than I want to give them credit for.