Great questions, jazz!
Bulls: I love bulls! And they're tasty too! :p As for bullfighting, I'm "Pro Choice"; if you want to go, go. If you don't, don't.
Flamenco: Mmmm.. I LOVE flamenco. I love watching it. I love listening to it. I love that it's alive and well even with the gypsy youth. I love there's a radio station dedicated to it ("Radio Olé") which you hear blasted from the insides of passing gypsy (often "tricked out") cars at all hours.
Siestas: I love siestas almost as much as I love flamenco. Although few people have the luxury to take a siesta/nap after lunch on a workday I'm glad that it's socially acceptable if you can/do. Sundays are great days for nearly everyone to take an actual nap after a big lunch. Like steve robinson, I would avoid a nap after lunch because I usually felt "yucky" the rest of the day. But now that I take after-lunch naps nearly every day I find that feeling doesn't occur anymore. Interesting.
Guitar: To me, the Spanish Guitar is synonymous with Spain itself. I love (classical) Spanish guitar music about as much as I love flamenco guitar music.
Smoking: Back in the USA I used to be nearly militantly anti-smoking. But now that I've been living here, and even before when I was just visiting Spain, I've found myself much more tolerant to the point I don't even notice it and don't think negatively of a person when I see them smoking. I don't like, however, coming home and smelling like "the bar" - which doesn't happen anymore really because I rarely stay out late in those kinds of environments. I prefer the outdoor terraces when the weather permits it. In the USA you often have "these people" whom will give a constant "fake cough" when seeing a smoker near them - even in a smoking section. Here, that never happens. Or if it does, it's ignored or they offer "the cougher" a drink of water.
Tapas: Mmmm... If there was every a tastier invention I don't know what it is. Tapas. Those tiny serving treats they most often give you for free with your drink order. Man, what a great idea. I don't even care knowing the bar has raised the price of my beer/wine just enough so that I'm actually paying for it indirectly. It's a nice detail. And besides, one shouldn't drink on an empty stomach.
Vagabounds. Hmmm... Not sure about this one. Are you referring to the homeless people whom live in Spain? If so, I find it a shame. There are so many (more) social services here in Spain to take care of the poor, hungry, and homeless that there really should be nobody sleeping under bridges or within the shrubbery. But according to an in-depth exposé on the homeless in Madrid by TeleMadrid last summer, many of these people PREFER to live in this way and do not want to go to the shelters or stand in line for free food. I'm not sure it's like this for every homeless person though. Some people really are too proud (or stubborn) to accept charity. But apart from homeless people, Spaniards work longer hours than we do in the United States in many cases. Sure, they may have a 1, 2, or 3 hour break for lunch but they also stay at work until 8 or 9pm! And you can't beat those 1 or 2 month summer vacations!
Speaking Loudly: Buff! Ain't that the truth! Sure, it's a generalization but I know a number of Spaniards whom, when they talk, I find myself pulling away so as not to stress my ears. Most people, however, do speak in what I'd call a "normal" tone though.
Saludos, MadridMan (oh, was I shouting?)