How many times have you ...

If I buy a reissue, it's to acquire a recording I didn't have in my collection or to replace one that was damaged through the years.  

That said, I did get one of the early reissues of the RCA Reiner "Scheherazade" a few years ago.  A friend had an original 1S and a 5S pressing.  We compared them and felt that the reissue was cleaner and more detailed than the original.  The difference was not subtle   His 5S sounded better than his 1S.  This example is the exception rather than the rule in my limited experience.

I also have a couple of original EMI City of Birmingham "Le Cid" that easily outperform the Klavier reissue.  I had the Klavier first and was gifted the originals.  

Just like a many manufacturing of environments back in the day, vinyl stampers were used well beyond their lifespan. Stamping machines were not properly adjusted, maintained at required intervals. It was all about pushing product out the door and not slowing production. Close to shift change? "Keep the presses moving along...I’m not taking the changeover hit on my shift". People talk about unmotivated and downright lazy practices by US automotive employees back in the day? Same thing at record pressing plants (and other industries). The 70’s (well into 80’s and 90’s) was an all time low for quality work practices in all of US manufacturing. Vinyl record production was no different. Mastering is a major part of an LP's sound, however, poor manufacturing practices and materials can kill any sonic advantages of vinyl. First pressings done closest to release date are probably the best you will find (outside of some audiophile version) IMO.

A lot of reissues suck, and it can be VERY frustrating dropping a lot of money to get somthing you'll NEVER want to play again. For example, I got suckered on the 200g DMM Rush remasters, ugh. Absolutely unplayable once you realize how superior the 1970s issues are. Then again, there are a few reissue gems out there - Red Hot Chili Peppers BSSM, Alice In Chains "Unplugged" and "Jar of Flies", for example.

Terrible expensive reissue and hi-end systems ... if the software is not up to that, what good is an expensive audio chain?
Inadequate sound engineer, digital console or other ... whose fault is it?

wlutke, I have no idea what millercarbon is talking about. I have at least 10 maybe 20 (never counted) exact duplicates manufactured at the same time in the same plant from the same master and they sound exactly the same except for the random pop or tic. Now when you are talking about copies made at different times in different plants from even the same master things are going to sound different mostly from different gain values. If they use different masters then they can sound a lot different. More modern masters usually sound better but not always. Millercarbon is right that for getting a great pressing all the stars have to line up but in plants that really care about their product they usually get it right. The commercial guys like Warner and Columbia don't care at all. Fortunately a lot of their great libraries is being given to plants that care. I have reissues of all the Weather Report albums except Heavy Weather and they are great. Sleepnighter is so much better than the original I almost cried and ordered a second copy. The reason I have so many duplicates is for exactly this purpose. I have two turntables which allows me to compare cartridges. I can match volumes with a test record and meter, sinc up the records pretty close and switch back and forth between the tables. I never thought about looking for differences in identical records.
Only millercarbon would do that. And, only millercarbon would hear a difference.