When I was growing up in the '50’s and '60’s, the word “tacky” meant “slightly sticky.” Sometime in, I think, the '70’s, it came to mean “vulgar” or “in bad taste.”
How did this new meaning arise? Is there a connection between “sticky” and “bad taste” that I’m not seeing?
From http://www.etymonline.com/index.php?term=tacky the two meanings are unrelated.
tacky (adj.1) “sticky,” 1788, from tack (n.1) in the sense of “an act of attaching temporarily” + -y (2). Related: Tackiness "stickiness.
"tacky (adj.2) “in poor taste,” 1888, from earlier sense of “shabby, seedy” (1862), adjectival use of tackey (n.) “ill-fed or neglected horse” (1800), later extended to persons in like condition, “hillbilly, cracker” (1888), of uncertain origin. Related: Tackiness.
The word “tacky” is a Southern colloquialism. It was coined by a wealthier or more refined and educated class for general application to those who were not sheltered by the branches of a family tree, who were “tainted.” Those who were wealthy and yet had no great-grandfathers were “tackies.” The word was used both in contempt and in derision. It is now nearly obsolete in both senses. There are no aristocrats in the South now, and therefore no “tackies.” No man who has the instincts of a gentleman is spoken of as a “tacky,” whether he can remember the name of his grandfather’s uncle or not. But it has its uses. It is employed in describing persons of low ideas and vulgar manners, whether rich or poor. It may mean an absence of style. In dress, anything that is tawdry is “tacky.” A ribbon on the shopkeeper’s counter, a curtain in the bolt, a shawl or bonnet, a bolt of cloth fresh from the loom may be “tacky,” because it is cheap and yet pretentious. In Louisiana the inferior grade of Creole ponies are known as “tackies.” [Horace Ingraham, Charleston, S.C., in “American Notes and Queries,” Feb. 15, 1890]
Applause!
‘Tacky’ is also the go-to word for expressing distaste with specific people or things, without having to get impolitely specific about the details. So a ‘tacky’ aunt is coming off her fourth marriage and is ten years younger than the rich uncle she married, and a ‘tacky’ purse has too much obvious expensive gold hardware and gratuitous alligator texture, but my grandmother wouldn’t be caught dead offering those specific opinions because she was taught to be nice and polite and not gossip. As an odd note, I’m only in my 30s, but I was raised the same way. Course, we also almost did cotillion, so there’s that.
Dr Fidelius, thank you very much. That’s exactly what I wanted to know. I can’t believe how quickly you supplied the answer. 
It’s really tempting to use the “ill-fed or neglected horse” meaning to connect “sticky” to “bad taste”. Something sticky, like glue > a worn out horse, such as might be considered fit for the glue factory > anything worn out > anything of bad quality. But I totally made that up myself just now, and a quick look at some dictionaries provides no support for this idea.
Unsubstantiated maybe, but very clever! 
I always thought the sticky/bad taste link was because every time I handled atack cloth I felt dirty and needed to wash my hands.
Every Doper should have etymonline.com bookmarked. It’s useful in a million different threads.
Remember The Official Preppie Handbook, by Lisa Birnbach? It was a 1980 bestseller, and it used the word tacky a number of times, IIRC. For example: “No jewelry. Tacky on children.” She didn’t come up with the “in bad taste” meaning by any means, but I think she helped popularize it.
I like it! As for me, my made up connection is that you use thumb tacks to stick a poster to the wall - an informal, not-very-elegant way to decorate. That is, of course, tacky. A classy person hangs framed art 
Hmm, I think several brands of that putty stuff used to stick posters to dorm walls without leaving a hole also have “tack” or “tacky” in the name…
the first time I heard it used made me think it was in the sense of a sightly sticky object that is unpleasant to touch, such as having a patina of accumulated airborne grunge on it. Eeew, I don’t want to touch it, it feels tacky.
No cotillion for me because dropdad was an outspoken Yankee so he was blackballed at the country club (have I ranted about how my father robbed me of my of my rightful future as a gentleman of Virginia lately? :mad:), but yeah, that’s the usage I learned. Not just because a lady or gentleman would not go into the details, but because the ladies and gentleman around you know exactly what you mean.
Note: Ladies and gentlemen know no race or financial level, they just know each other when they meet them.
Fer sure. This came out when I was in seventh grade and that’s about when I would have started using the word.
The origin might be the 1963 Pete Seeger hit song “Little Boxes”, which were all made out of ticky-tacky. It was a satire on the post-war era, when new subdivisions were composed of rows of identicall and cheaply built houses. The song drew attention to the mass conformity of Americans in the 1960s. So among other connotations, tacky might have grown from that to represent things that were poorly made and/or stylishly undiscriminating.
The entire lyrics: Song Lyrics to Little Boxes, by Malvina Reynolds
The Ngram viewer shows a rise in the use of the word tacky beginnning around 1963.
Jtur88, I like this theory.
Then there is Tachy which is totally different.
A Virginia lady of my acquaintance (my brother-in-law’s mom, in fact), a resident (at the time) of Hopewell, also used the word “common” to indicate the opposite of a lady or gentleman, and synonymous with “tacky” in this context.
Ex.: “She is so common.” (The italics indicate the peculiar emphasis the word had when used in this context. To clearly convey that she wasn’t addressing scarcity or rarity.)
Then there’s the tack piano, which is associated with honky-tonks and such (pretty tacky places).
From your link:
Hers is the only version of the song I remember. Seegar’s cover made it into the bottom of the the Billboard Hot 100 in January 1964. A group called the Womenfolk had a version that charted slightly higher in April. Neither rings any bells. I’m sticking with the original.