It's so unfortunate to hear a medical student talk like this about his peers.
There are a quite a few problems with your assertion here.
First, every doctor with an MD after their name who is eligible to practice in the US has passed the same licensing exams as USMDs. In fact, that is the exact purpose of having standardized licensing examinations - it ensures that everyone who passes them has acceptable and comparable competency (I state the obvious here because you seem oblivious to it). Of course I am not referring to common wealth or Indian MDs who have challenged speciality board exams after practicing in their home countries - but even then the requirement for such MDs to sit for USMLE examinations (or FLEX examinations, depending on how long ago we're talking about) is ALWAYS waived because the ACGME and state licencing boards deem that such MDs have already attained an equivalent level of competence. Caribbean schools - as part of their US accreditation requirements - only award students an MD after they have - among completing all other graduation requirements - passed Step 1 and both parts of Step 2.
So your claim that caribbean schools "slap an MD" on "anyone with a wallet" is just plain wrong; everyone who is awarded that degree has earned it. There is just no sense in arguing otherwise.
(And it should be noted that caribbean students are required to submit Step 2 results in order to be eligible to apply to ANY speciality through the NRMP - something not always required of US medical students).
Secondly, in some of your previous misinformed (or ignorant) posts, you seem to question the quality of international MDs. The reason I say you are misinformed or ignorant is that the evidence says otherwise. (Evidence? Oh you know; the same type of evidence that all MDs learn to apply to clinical situations... makes me wonder if they taught evidenced-based-practice properly in your US school) . If you can stop insufflating smoke up your own anus for long enough I would encourage you to take a look through this recent BMJ article:
http://www.bmj.com/content/bmj/356/bmj.j273.full.pdf
There are several other articles out there that have been published in recent years that echo these findings. Of course your problem is with "Caribbean MD's" specifically however, if you look at match data (not that you have to as a US med student because you'll be awarded interviews just by virtue of country in which you studied basic sciences) you'd know that the majority of "independent" applicants in the NRMP main match are US IMGs - the majority of those being US Caribbean students.
So the article I just shared with you is indeed relevant to this discussion. While the difference exposed by this articles is significant, it's admittedly not impressively large. So the best we could do in terms of generalization here is to say that there probably isn't much of a clinically relevant difference between US and Internationally educated internists practicing in the US.
Further to that, and as an American citizen, I find your commentary un-American and as a future doctor I question your commitment to US patients. One of the best things about the US is that we base personal advancement on merit - not on extraneous metrics (like someone's country of origin, or where they were educated). In Canada, for example, IMGs (regardless of their nationality - so this applies to Canadian IMGs) can NOT apply to the same residency positions as Canadian or US MDs. If we assume that caribbean IMGs have lower undergrad GPAs and MCAT scores than their Canadian or US colleagues and we know that there is currently no data out there that suggest that these metrics are predictive of future healthcare outcomes what this effectively does is it denies the Canadian healthcare system the opportunity to access the best physicians for a given job (i.e. specialty). This DOESN'T currently happen in the US because BOTH IMGs and US Seniors apply to the same residency positions. I'm personally thankful that we're a country who values medical students' proven abilities over their pedigrees.
Also, in some posts in this thread some have asserted that US students go to the caribbean because they can't don't get into US schools. Well, (in the majority of cases) you're exactly correct. But so what? I can't think of a more brain-dead point to make.
So you say you want to stop what Caribbean students are doing? Well, this is EXACTLY what Caribbean students are doing: The fact of the matter is that the US is going to be short 20-30K physicians within the next 2 decades and no matter how far you burry your head in the sand these Caribbean schools that you seem to have so such a disdain for are fulfilling a US necessity -
your mother and father, in fact, are VERY likely to be cared for at some point near the end of their lives by an MD who was educated at a Caribbean school - which is great because they're likely to experience a better outcome than if they happen to be seen by a USMD (You should let this last point sink in for a while before you post any knee jerk response to my post). What's also funny about this point is that if US schools and the US government where to pull their socks up and expand existing US med schools to the sizes that they ought to be, GUESS WHO would then be able attend a US MD school? That's right, all those students going to the caribbean would be at US schools.
(However, if you're talking about Canadian students - due to relatively more intense competition in Canada, many decide on the Caribbean because the average med student there goes through 3 rounds of med school applications before being accepted - many people don't have 3 years to waste. A good number of Canadian students end up practicing in the US after attending Caribbean MD schools and many have undergrad GPAs and MCAT scores that would blow most US students out of the water - could you imagine if Canadian citizens could access Title 4 funding - you might not have got into your US med school! Also, please note that Canadian students probably make up ~20% of Caribbean medical schools; your attack on Caribbean students is thus even further misplaced).
Take a second and think about what you're saying, before you share your ignorant, close-minded views.