I won't presume to speak for everyone, but I can tell you why I think the Caribbean schools are sub-optimal.
Everyone at a Caribbean school is there because they did not get into a school in their home country (generally the US and Canada, hereafter called 'American'). They have poorer GPAs, MCATs, and CVs than do American students. Fine. Let's divide those students into 2 groups: those who weren't serious about their studies and weren't well-prepared for the MCAT, but who are intelligent and dedicated to becoming a good physician, and those whose scores are, um, an accurate reflection of their true ability.
For the first group, the Caribbean schools are a wonderful second chance. All that group needed, once they got serious, was someone to give them a fair shake. They're bright, they're motivated, and they take that second chance and run with it. Those are the people who pass the boards well, approach the wards with enthusiasm, and make good residents.
The second group-- those who truly aren't bright or dedicated enough to make it through medical training-- are what give me problems. The Caribbean schools are famously for-profit institutions. They admit without discretion. They admit for 1-2 years of "premedical" studies, or "half-time" studies, or whatever-- anything to make a buck. People fail, are re-admitted, fail... The schools themselves have *no* incentive to winnow them out (which they could do-- they could have a single entry time, they could conduct real interviews).
And they shaft people on their clinicals. The quality and rigor of your clinical sites varies enormously. Some are glorified observerships, some are slave labor, many award only A+s and As, nothing lower. Again, the schools have little incentive to change any of this. I feel that if you came out of a Caribbean school with good board scores and a solid fund of medical knowledge, you are to be especially commended because it was most likely entirely of your own doing, *despite* the barriers imposed by your school.
OP, I'd take a seat in a "real," national medical school-- one with its own hospitals and its own clinical faculty, who will train students to become residents in its own system-- any day over a for-profit Caribbean school. Whether that means Sackler, or Ireland, or Australia is really up to you (though they're three quite different countries: make sure you'd be happy living there).
Oh, and please let's all avoid the "there's this one guy" fallacy. Yes, there's the brilliant Hopkins grad who hates attending on the wards and just wants to get back to his lab. Yes, a woman from SGU is now attending in rad-onc at Harvard. Yes, that Ross peds resident is so full of warm fuzzies, his patients love him to death. As with any statistical distribution, there will be outliers, but they don't affect trend.