So just out of curiousity then, what exactly are they referring to when they say some car brands are reliable and others aren't? If my VW's repair history is no indication that VW is unreliable, what exactly goes wrong with "unreliable" cars?
It depends on who's defining what reliability is, but generally speaking, it means that, if proper maintenance is done, the vehicle does not experience some sort of failure, not counting "normal wear" items going at the age which is considered the norm for these. In that case, normal maintence should be able to identify those items that are close to being worn out before a failure occurs.
So what does that mean? A 10 year old car could very likely need a new alternator. A 10 month old car shouldn't. A 10 year old car could have problems due to corrosion or wear of components to other parts of the electrical system as well; but a 10 month old car shouldn't.
A transmission should be good for well over 100,000 km before needing repairs (many good transmissions, which is where my bar is set, should easily go 300,000km +). Failures before then could be considered a reliability problem. But, that also depends on whether the car was abused, or maintenance was neglected.
Yes, VWs have a reputation for bad reliability, they earned this during the 80s and into the 90s. Other brands have also earned reputations, for good and bad reliability. But what that simply means is, in terms of percentage of vehicles considered unreliable, that percentage is either higher or lower than what is average across the board. That also means, you could have a vehicle from an unreliable brand, yet have a very reliable car, or have a vehicle from a reliable brand, and own the worst lemon ever made.
Based on the majority of the items you listed, you've obviously been unlucky in that everything seems to be happening in such a short time frame, but these are almost all items that can be expected to be either maintenance, or at the end of their useful service life (worn out).
As for your heater core going because the coolant was never flushed. That's normal. The people who've been able to escape that, it's pure luck.
I married into owning a VW. It was never on my list of vehicles anytime I went to buy. That said, while it is a relatively young car (2003 with only 106,000 kms), I have had no major issues with it, except for: glow plug under warranty (apparently changed to a revised design so that it shouldn't happen again), a suspected loose cable on my temperature control for HVAC (when it's warm enough, I'll crawl under the dash and fix it in probably less than 5 minutes, but it's stuck on hot right now, so I'm not too worried), a battery that is very weak, which I am replacing this week (almost 6 years of life, one of the bettery batteries I've had; norm was about 4 years, the worst less than 2) or, repairs related to a less than perfect repair job at a body shop after my wife was rear-ended or stuff that I screwed up myself (wasn't paying attention one morning, and backed up while plugged in, yanking the cord, which in turn, yanked the cords of a couple of other things, which I since fixed).
My impression of the brand has certainly changed. I know that some still complain of electrical gremlins, their automatic transmissions (but then so are many others), and some engines of theirs have been questionable, but there appear to be no electrical gremlins in our car, we have a manual transmission which many consider rock solid, and one of their coveted diesel engines (non pumpe-duse design).
