It is a lost art somewhat, in part due to the speed at which storylines progress today (in the 80s you had to play feuds sometimes as long as 4-5 months to get the most business wise out them by playing them on the house show circuit, you didn't have to constantly change things with live main event matches on TV every week and monthly PPVs).
There were several epic turns in the 80s. Some you did sense were coming but that actually made it more interesting, you started watching to see if in fact they would go through with the turn or not, like Paul Orndorff in (I believe that was in 86 vs Hogan) and Savage in 89. Turning Savage face took much more time in 87-88 and was a gradual process. HBK turning on Jannety in 92 was another one that was sold for weeks on TV, teasing the tension between them, which exploded when Shawn blamed Marty (incorrectly) for costing him a match vs Flair.
Others that were shocking was Andre in 87 (he'd been a beloved fan fav for 20 years, no one saw that coming), Flair in 85 (he might have been a womanizing partier but he was all American, sick of the evil Russians denigrating his country) and in 89 (his respect for Steamboat, feelings of owing Sting for defending him, hatred for Terry Funk), Lex Luger in 88 (dumping the Horsemen), Undertaker in 92 (turning on Jake Roberts over his violence towards Elizabeth), each of these was a pretty huge event.
Again, I blame the way the product is showcased more than the performers, storylines, except maybe at the very top of the card, are not given much time to really take shape, so character development, including heel and face turns, are not executed as well.