The "real coding" comes in where you're adding unique value to whatever it is you're developing.
If you're spending time re-inventing the wheel and choosing to write what will - almost inevitably - be less comprehensive implementations to solve common problems then you're not really adding value.
Fundamentally therefore you trust the generated code (or packaged/library code) until you have good reason not to.
However, I suspect you don't mean "code" you actually mean "markup" (i.e. HTML and, by extension, CSS - and javascript, though that's code again!) and that's a somewhat different question - and a somewhat broader one since there are a number of possibilites in terms of how that markup is specified and generated. Old web forms code does things that are "not nice" although, as it turns out, are more than adequate to a lot of purposes whereas with MVC you have very fine grained control of what appears in the client browser. (And with the latest version of web forms MS has attempted to ensure that their markup is a lot cleaner.)
Ultimately if you're putting up a "public" facing website (which is the implication) you want to have a high level of control over the markup. There are any number of ways you can do this with the MS stack - ASP.NET MVC is the "in house" tool - there are others.
