Well, this is not exactly an unknown pleasure, but it's still a great way to spend the second Sunday of every month, or any month. You won't get insane bargains on undiscovered pieces here (maybe if you go at 6 am, but nobody I know, or probably would want to know, ever has...apologies to early risers), but you will find cool stuff that is different from the usual furniture and decor options. They have tons of vintage clothes and new junk also. Recommend going around ten, before it's too hot and too picked-over...have a frozen lemonade and walk around then go to brunch after. Of course if you go late, you can take advantage of sellers who don't want to truck stuff home.
The Rose Bowl is a total freaking treasure trove for shabby chic / cottage aficionados/aficionadas. I am not one, but long ago I had a phase, and I'm still amazed at the numer of vendors catering to this taste. If you don't want the hassle of refinishing that flea-market find in distressed white or cottage-rose pink, someone at the Rose Bowl will have done it for you, and for much cheaper than Pom-Pom or Bountiful or Shabby Chic itself.