Is buying a redial a huge no-no for vintage watches?
I've got an umbrella to hand, so when the collectors here decide to stone me for this answer I'll be ready.
Is a redial a huge no-no?
The answer to that depends entirely on what you want.
The people you are talking to here (me included, this answer is purely playing Devil's Advocate) are collectors. Collectors insist on one thing above all else: originality. If you are buying for a collector, then rule out the redials and learn the obvious giveaways to spotting one.
On the other hand, there are a lot of people out there who want a period looking watch or something that is totally different to the norm. Now, there are a lot of watch makers and watch tinkerers out there with varying levels of skill who will take a totally worn out vintage watch and turn it into something very useable and very wearable. I have seen some appealing "Mumbai Specials" being offered on eBay that have good looking cases (though polished to the point that the original facets have vanished) with brightly coloured dials and incorrect movements. Bought carefully - and I really stress this, because you don't want a watch that's only right twice a day - these can be a fun watch. They are NOT original. They have limited or no value. But, if you want a bright red "vintage Omega" to match your bright red brogues then £20-50 for a bit of fun might be something that appeals to you. In which case - you go for it. Don't worry what others may think if you like it.
What's far more dangerous is the watch that has been refinished with a repainted dial that is pretending to be an original vintage piece. This is where the Forum gets worked up and the unsuspecting buyer gets taken for a ride. These watches are also not original and have the same sort of value as the "Mumbai Special" ... but the seller isn't being open and is asking the full market value that an all original piece might bring. This is where you have to exercise all due diligence.
If you are looking for an all original piece and you don't have the hands on experience that gives you the ability to tell right from wrong, then you are better advised to seek out a reputable seller. Still ask lots of questions. Good sellers don't mind questions. Good sellers are people who have a love of these watches themselves and will thoroughly enjoy talking about them, even more than you will want to.
Before you start contacting the sellers, though, you need to be sure of what's important to you in the purchase. Do you mind if the case has a nick? Or the dial a slightly uneven patina? Bracelets add to the value of a watch, so are you happy with a generic leather strap? Even the correct Omega buckle has a higher value than you might expect. When you get into the particularly desirable references, the prices rise more steeply than you would believe possible. Obviously your own budget is an important consideration and you may or may not want to disclose this to the seller.
A great place to start is Omega's own vintage reference pages which has lots of pictures and detail. The Seamaster range can be found here:
https://www.omegawatches.com/planet-omega/heritage/vintage/
but when you open an individual link, open it in a new tab otherwise when you click the back arrow you will lose your place.
Finally, when you do find something that you like there are lots of people here who would be happy to give an opinion on it. Secretly, we all wish we had someone who was willing to spend the time and effort in finding a perfect gift (watch) for us and will give unbiased views.
Happy hunting.