Well, I will start by saying that I have never seen the stupid chihuahua movie, so I don't know if it is any good or not.  Therefore, I will be judging a book by it's cover.  

People enjoy movies not just for entertainment value, but also because there is less thinking involved.  On top of that, people enjoy stupid movies.  The first stupid movie that I recall seeing was "Dude, Where's My Car?"  I believe that so many people saw it because it was so stupid that it was funny.  There are tons of movies like these, but why do people constantly go to see them?

One reason may be because somebody has seen every other movie out in theaters and watches the movie out of boredom.  There are people so boring that instead of living their own life, they go to the movies and design their life according to what happens on the big screen.  In the case of the chihuahua movie I don't think anyone would try to mimic it, but rather adapt it to their own lives.  

Another possibility is that people simply like chihuahuas.  I, on the other hand do not like them.  I think they are ugly.  If you like something, you are more likely to watch a movie about it.

To me, it appears that the movie is a doggy chick flick, and I will now use the phrase "bitch flick" in the rest of the entry.  This bitch flick features dogs that are owned by celebrities and live a much better life than most of the people watching the movie.  Not only that, but these dogs are in love.  A human type of love with an infatuation and all that mushy stuff.  From what I can imagine, the movie is similar to a doggy soap opera.

I will never truly understand people.  Especially ones that pay $10 to see some ugly dog love story musical.