Just my opinion, but Colombianas make up the majority of my chica diet and I find that the Colombianas' bad attitude seems to be directly related to the amount of time she spends every night talking to someone who is trying to get her to sleep with him for $60 or less.
I don't track down girls according to their nationality. I pounce on the most attractive women I can find in classic terms (great face, great body, some class, a touch of personality). I don't care where she is from but the majority, 4 out of 5 or better, are Colombianas. YMMV, but these girls don't normally come off $100 because they don't have to.
Just the way I see it, and from what they have told me across the pillows, they get really tired of the guy who looks like he is there on a tight budget approaching them and the first thing they ask is "how much" then they offer her half as much as she asks for and insult her when she stays at her price. Yeah, her bitch shield is up if that is what her take is on the guy.
I have had good success by dressing a little less scruffy but very casual and by smiling at her when I approach and getting her to smile back. Once her shields are down, she's just a girl, in my humble opinion but your mileage may vary.