I never thought of myself as being rude; I just ate spaghetti noodles like I ate all other noodles in my life. I pick it up with my chopsticks and stick it in my mouth, eating my way down the noodle. Is this really that rude? I’ll tell you one thing, it’s definitely not because I think it looks “cool.” Who eats a certain why because it’s cool? Why would the OP even think that?
The reason I thought that is because the people I see doing it are either current young celebrities, who seemingly do everything they do for effect, or young people in my community, who have the under-21 mind-meld, in which they share wardrobe choices, slang, and various affectations. Also, having been that age myself, I well remember the attitude of “Who has time to learn to do X? I don’t bother with THAT; I do it MY way!”
Eating pasta with a spoon is for little kids and people with no table manners. It’s like putting a napkin on your chest or holding your fork with a fist. It might be effective, but it just looks dumb.
Ah, okay. So it’s not a “I’m cool because I eat it like this!” but rather a “I’m cool because I say screw societal norms!”
It wasn’t until college that I finally found out what the spoon was for. It was harder to use it than not, though.
I don’t have any problems twirling spaghetti noodles, but I was at a Vietnamese restaurant the other day and I had a hard time eating a bowl of soup with long thin rice noodles in it. They gave me a spoon and offered chopsticks, but I ended up using a fork to twirl the noodles into the spoon, with limited success.
Yes, I’ve cooked some Asian things that call for a few vermecelli like noodles, nothing like the amount of Western pasta I see in a dsih. We were quite rude/child like/silly in eatting them; I’d hesitate to try and eat them at a restaurant. 
The twirling with a spoon’s already been explained; do you want to know how to twirl the noodles with chopsticks?
Twirling with a spoon is just more things to wash.
A better question is why Americans do such odd things with a knife and fork…an easy job made difficult!
Nobody around here twirls their pasta. But, we also put meat in our sauce. If you twirl, the meat gets scooted out of the way.
The most common way that I have seen in Tuscany is to separate out a few strands with your fork, and give them a few strategic pokes to bunch them up. This can kind of look like the person is stabbing their food a few times before bringing the fork to the mouth. There is usually something in the sauce (chunks of meat, fish, veggie) that can help you “anchor” the noodles around a more substantial piece of food. They might flip the fork once. This method is very neat and doesn’t result in any long pieces hanging down. Spoons are completely absent.
I seem to remember some comments about how twirling (turning the fork over several times) was something done by people in the south of Italy and in the US – and the tone was a little disapproving.
When I worked in Italy (Romano d’Ezzelino, Mozzate, Milano), most of my italian coworkers would twirl the pasta; some cut it, causing bouts of the rolleyes and remarks about their mamas not having taught them proper manners, eh! Eating out, if you asked for spaghetti you got a spoon (spoons were brought to the table only if your request needed one, i.e., spaghetti or soup). One American remarked that he’d never seen people twirl their pasta with a spoon before and one of the Italians answered “eh, she do it too!” meaning me; I explained I’d learned it from my Zanni grandma.
As stated in my earlier post, my Grandmother was Sicilian. She considered it an insult to be called an Italian (but then Grandmother was hard-headed about a lot of things). There’s a big divide between the North and South. The only thing northern Italians and southern Italians can agree upon is that Sicilians are gutterslime. The only thing northern Italians, southern Italians and Sicilians can agree upon are that Sardinians are even lower than gutterslime.
Note that I’ve not yet visited Sicily, so all I have to work with are the stories of my deceased Grandmother, born in Sicily, and my father, raised in Italian neighborhoods in Manhattan during the Depression.