As an Asian American let me chime in on what I've noticed over the years as well as my own preferences.
Many Asians do prefer white men. Partially this is based on many Asians' perception of whites… We do get to see American movies, and white men are typically portrayed as being very manly and masculine. They are James Bond, they're Indiana Jones, they're cowboys... With that masculinity, they're also the charming dashing hunky man who gets the girl. They're smooth talkers. They're sexy.
Meanwhile, in Asian movies, even if we take the hunkiest of the kung-fu stars, they're not as smooth in picking up women as they are with their white counterparts. Generally, Asian men are portrayed as being more soft spoken, they are less masculine, and they're maybe more clumsy and silly.
Another factor is, all Asians look similar to each other... same colored skin, same hair color, growing up where everyone around you has black hair, you end up craving something very different. American kids grow up seeing all different kinds of people of different colors and ethnicities. A blond person isn't as "special" to a white person as it is to an Asian.
I think those are some of the factors why Asians (not just gay men, but women as well) like white men better.
Now the other way around... what I've observed is there are far fewer whites (gay men and women) that prefer Asian men, especially when you talk about the younger whites. Why is that...
A big part of it goes back to how Asians are portrayed in the media. Look at how many Asian men are on TV or in the movies. There are very few outside of a kung-fu movie (Jet Li, Jackie Chan). Who are some Asian men who are in the media but not a kung-fu action film hero? Not many. John Cho (Harold from Harold & Kumar)? B.D. Wong (who is actually gay in real life)? Can you name many else?
When there are Asian men on TV though, who do we see? William Hung! And other nerdy looking Asians who speak with a thick accent and act like idiots. They keep pushing further that stereotype.
For their parts, John Cho and B.D. Wong has shown that you can be Asian, not speak with an accent, and be good looking. Unfortunately they're not bigger in the media.
But still, we're missing the Asian leading men.
White women typically don't go for Asian men because they're not very masculine. They're not what you consider "manly", especially when you compare them with white men.
Gay white boys (those in their 20s) don't go for Asians because I think they've got certain stereotypes about how Asians look and act, and that just turns them off.
Let's take a look at mainstream porn. We hardly see Asians in Western porn. In Western porn we have every sort of ethnicity well represented... blacks, Latinos, Russians, eastern Europeans.... what have you. But very few Asians. I can't remember his name, but he was quite big back in the 90s, and I believe he's half white half Asian. Catalina made some Asian-themed movies-- Cream of Sum Yung Gai, Chew Manchu, Brandon Lee Wicked, Fortune Nookie. I've seen them... they're pretty bad. I don't think the Asians in there were very good looking. I've seen better looking ones. Van Darkholme comes to mind. And plenty of Japanese porn have lots of great looking Asians. Again, too bad they're not popular.
Speaking of porn, by the way, the stereotype that Asians have smaller dicks doesn't help.
Now, the older white men, they like Asians because as some have said, some Asians are desperate and they'll take whatever white man will have them. Some also like Asians because they think Asians are more submissive, and I have to say from what I've seen, that may be true. This is also why you see many older white men with Asian women.
What I've seen lately though, is the tide is changing. Thankfully, compared to the 90's, I think whites are more open to Asians now. And more Asians are open to other Asians as well. I think a lot of it has to do with the younger generation of Asians who were born and raised in America from immigrant parents are growing up and they don't necessarily fit the Asian stereotype of nerdy unfashionable dorks who don't speak English. I think whites are also more knowledgeable and more exposed to Asian culture. Asian culture isn't as mysterious as it once was.
For the record I'm in my early 30s and I have a white boyfriend who's a couple of years older than I am (and no he's not fat, though he's not a muscular hunk, I love him all the same). I was the first Asian he's gone out with. We met on an online dating site, and he normally wouldn't have emailed my profile because he's not into Asians but he found something I said to be funny and decided to email. When we first met, he was prepared to speak very slowly to me, not knowing I speak English fluently (communication up to this point were all emails). He was also shocked at how much I knew about classic American TV, or how I loved a big juicy burger with the works on it, and all-things American. And when we finally had sex, he was also shocked that my dick was not the small little Asian dicks that he had heard about. It goes to show what his stereotypes are (or were, I should say) about Asians.
If you ask me in the 90s if I would have an Asian boyfriend, I would've told you no way for all the reasons above. So those stereotypes are not held just by whites, but also by other Asians. But if you ask me today, I certainly would not mind having an Asian boyfriend.
(By the way, I realize you may not necessarily agree with what I've said above. They are just my observations and opinions from speaking with friends and others. There are always exceptions to every rule.)
Well-said, I totally agree !