> ...I have a personal theory that the overwhelming aroma and taste of hops in a beer can be used to mask many errors and missteps in the brewing process...
For what it's worth, more hops absolutely masks errors in brewing. It's something that any homebrewer finds out very quickly.
IPA's/etc are very easy to get a drinkable beer out of no matter how many mistakes you make. (To be fair, it's not just IPA's that are forgiving. Weissbiers are actually quite easy to brew due to the yeast hiding off flavors nicely, and ambers can be easy due to lots of caramelized, unfermentable sugars hiding off flavors. You can overdo the sweetness in an amber or mess up the fermentation in a wheat more easily than you can make an undrinkable IPA, though.) That's not to say that really good IPAs are easy to brew, just that you'll get something drinkable no matter what.
Any commercial brewery _should_ be beyond basic mistakes, but scaling brewing is hard. What I'm saying really only applies to homebrewers, but I suspect it carries over to smaller breweries as well.
The hardest beers to brew well are actually Pilsners, Lagers, and American-style pilsners/mega-brews. Anything with very clean, crisp flavors. I hate to say it, but if you want to really test your skills, try brewing a miller lite clone... This is especially true in homebrewing, where proper lagering/aging and fermenting at low temps needed for lager yeasts used by pilsners/lagers/etc is difficult.
At any rate, my hat is off to Czech brewers. Trying to brew a really good pilsner or bohemian lager is damned hard to perfect, and it's an absolutely sublime style when done right. Sadly, it's somewhat rare to find a brewery in the US that can do it well.