1. Probably, but everyone's a critic.
2. Definitely. Many of them are perfect just as they are. There have been remixes of some of my favorite albums (Megadeth’s "Countdown to Extinction" for example) that altered the sound so much it wasn't the same anymore.
3. If the song is good, small changes would not affect its popularity. Maybe if it sounds horrible it probably won't become a hit, because the listener is used to a certain degree of quality.
4. Yes! Although every decade has many distinct sounds, it's usually one everybody associates with a certain decade.

1. Put a mix in front of a group of engineers and what do you think will happen, would any of them agree on a mix?
2. Over the last 30 years of successful hits, do you think there would be one mix you would leave alone?
3. Would a small change to a mix make or break the hit? Or how much of a change would effect the hit?
4. Does every decade have a sound?

   1. In my experience, many would agree on a good mix but at the same time, if asked what they would have done, many of them would have had their own opinions, which would differ from person to person.

   2. There are many, many mixes I would leave alone. There are also more than a few that I would have changed, some slightly, some greatly.

   3. I don't think small changes would make a difference. A good song is a good song. As long as the mix was solid all the way around, then it wouldn't matter. ( A song like Yesterday would have been successful with or without the string section.)

   4. Absolutely. Much of the time, the instrumentation and production tools that were popular at the time are responsible for making the "sound".

   1980's - Things like the DX7 - the Rhodes patch on that synth was used in hundreds of 80's ballads. The Linn drum, Fairlight, digital delay and reverb, all played a part in the 80's sound, as did the emergence of Rap as a commercial product.

   The 1970's gave us a lot of songs where the drums sounded "dead", Wah pedals were used on guitars, and of course, disco. You can hear a lot of B3, Wurli and Rhodes in the music of the 70's.

   The 1960s's were, I think - the most diverse years. Music styles ran the gamut - the early sixties had teen stars like Frankie Avalon and Fabian, Folk artists like Peter Paul and Mary, Dylan.
   1963-64 brought in The Beach Boys and Jan and Dean, R&B from Motown/Stax, along with The British Invasion. 1966-67 brought Psychedelia, and towards the end of the decade, acoustic-based styles by artists like Joanie Mitchell and CSNY.

   The 90's gave us grunge. Nirvana, Stone Temple Pilots, Pearl Jam. LOL, I call it the "I'm so messed up" decade, because so many songs had lyrical content that was self-deprecating.

   2000 - 2010 had many different styles - some songs were patriotic in the months following 9-11, others were American Idol-based. Throughout all of this was a pushing of the envelope in terms of sexuality. Innuendo gave way to outright descriptive.
   Pro Tools became a studio standard. Analog decks and 30 ft consoles gave way to powerhouse computers and control surfaces. Copy-Paste became a standard process in which to produce music. Home audio systems gave way to MP3's/iPods.

   I've only given the broadest of examples here. There are many more examples of what defines those decades.

   IMHO of course.

1. Yes, some would agree, but it would depend very much on the genre presented. Engineers tend to be 'fans' outside of their own genres and 'critics' inside.
2. I don't really have any problems with most released mixes. I don't necessarily agree with all things and their placement in music I hear, but that doesn't mean that any changes I could make would make it a better listening experience.
3. The only changes in well known and successful music that would cause a shift in perception is the performances. The only mix changes that could affect that, would be covering up the magic existing.
4. Every decade has an influence on every decade since. The 'sound' is more long the lines of musical arrangement and songwriting although the growth (maybe not the right word!) of technology is certainly a factor in the sounds related to a certain definable era.

how many recording engineers does it take to change a light bulb?

20. 1 to change the bulb and 19 to stand back with their arms folded and say "I coulda done it better." ;)