I agree. Many films set in past decades seem like it is just people playing dress up, while very few actually feel and look like the decade they are set in. That is one of the things I liked about Days of Future Past, and I have faith in Singer delivering the same feeling for the 80s.
For an example of one film capturing an era perfectly while another felt like dress up, look at Boogie Nights vs. 54. Boogie Nights felt like the 70s.
I kinda liken bad 80s-set movies to those 80s themed parties you see in clubs(though I think high schools also have them occasionally), where half the guys show up in "Frankie Says Relax" shirts(because they don't know what else to show up in), the other half dress up like they are from Miami Vice, and half the girls are wearing day glow, leg warmers and headbands and the other half are dressed like Madonna, because...
80s!
I also think there's a stark contrast to the shallow pop culture thing. It's the more "try to keep the movie as modern as possible, and only give the most SLIGHT nudges it's still the 80s". It's basically, to put it bluntly, like people say, "Hipsters look kinda 80s, just take off those fedoras, give them Cosby sweaters, they already have the thick rimmed glasses, have them talk about stuff and put on some Quarterflash or Rick Springfield in the background.... and that's 80s!". They did similar things in the 90s with passing Grunge kids off as 70s kids. Sometimes it works, somethings it doesn't(well, most times it doesn't). I've found, most of the time, the only ones who take "era spirit" seriously are those making drama movies. I mean, visually, Argo did a damn fine job capturing the "look" of what the late 70s/early 80s looked like.
I think, now more than ever, it's not hard to research the more recently past decades. There are a LOT of videos you can find online, hell, even on YouTube. Commercials, television clips, even home movies from older decades that LITERALLY show you what life was like back then(you don't get more literal a window into the past than home footage of people shooting camcorder footage of their family or walking around town). It's not like the 1800s, where you don't get much literal video references, and have to do real book research to make a movie feel authentic.