I am not sure I agree with all of the advice. It sounds like you are looking to purchase for a good resell. If so - here are my recommendations on road bikes.
Anything Campy I don't agree with. Not all Campy collectible or even desirable.Campy Record is new top-of-line. For vintage, if it's not Campy NR or SR - or in certain cases maybe Victory - then it's not very desirable. Some older Campy like Valentino is also OK - but for 70s-80s I would stick with NR or SR.
Modolo, Universal, and Mavic are lesser-quality brakes than Campy NR or SR. Still - some really good bikes came with Universal or Weimann brakes. If the bike is all Campy NR or SR including cranks, headset, bb, pedals, and derailleurs then perhaps it originally came with other brakes - but if they are found on a bike you should note the brakes are much less quality (and a lot less expensive) than Campy NR/SR.
Anything that sounds Italian?? No not really. Univegas and some other so-called Italian bikes are really not very valuable. A lot of "Italian" names go unsold on eBay or sell for just a few dollars.
Reynolds 531 or Columbus SL or SLX for vintage bikes. Anthing else is not very desirable. Reynolds 853 for more modern bikes. Anything else is not worth it. Tange or Ishiwata??? No way.
Anything with Presta valves? There's a lot of pure junky old bikes with presta. This in no way indicates a good bike to buy.
Lugged and especially pretty or pointy lugs indicate good workmanship and helps resell the bike. But a fancy cutout in bb indicates nothing about the value of a bike. Forged Campy dropouts are also a good indicator of a good bike - moreso than "anything that sounds Italian".
A Brooks saddle in good condition is a great asset.
I'd stay away from any Simplex, especially the plasitc 70's stuff.
Shimano 600 in ornate "Arabesque" style looks good but is less valuable than the Campy NR/SR counterparts.
Bottom line for me - lugged steel Reynolds 531 or Columbus SLX with Campy dropouts, and all Campy NR or SR including brakes for a vintage 70-80's ride. For a more modern 90's or newer same steel or else Reynolds 853, and DuraAce or Ultegra.