Word for “decorated too much”

I would use the verb "overdo." What exactly has been overdone is usually pretty obvious. Saying something is really overdone usually means it's tacky or overwrought, which I think is what you're looking for.

Adjectivally, you could describe something as baroque:

extravagantly ornate, florid, and convoluted in character or style
_{from dictionary.com}

or florid:

flowery; excessively ornate; showy
_{from dictionary.com}

Verbwise, I can't think of any single word that encompasses that extent of a description, unless you want to go for something like overembellished with an additional phrase to point out how far beyond the pale it's gone: "He had overembellished it to the point that it became a grotesque parody of its potential nature", or "he had embellished it well past the point of baroque floridity."

Ragged or shabby means unattractive. When a more complex decoration is applied to something it becomes ugly. It doesn't look professionally made.

How about gaudy?

gaud·y
–adjective, gaud·i·er, gaud·i·est.
1. brilliantly or excessively showy: gaudy plumage.
2. cheaply showy in a tasteless way; flashy.
3. ostentatiously ornamented; garish.

The word that springs to mind is: Overdecorated.

Make gaudy... over-decorate.

Maybe bedeck

There's actually one word to refer specifically to this. It's "kitsch":

a representation that is excessively sentimental, overdone, or vulgar

How about garish?

From WordNet (r) 3.0 (2006) [wn]:

garish adj 1: tastelessly showy; "a flash car"; "a flashy ring"; "garish colors"; "a gaudy costume"; "loud sport shirts"; "a meretricious yet stylish book"; "tawdry ornaments" [syn: {brassy}, {cheap}, {flash}, {flashy}, {garish}, {gaudy}, {gimcrack}, {loud}, {meretricious}, {tacky}, {tatty}, {tawdry}, {trashy}]

the word you seek is ungapatchka. (it's yiddish)

Urban Dictionary:

a Yiddish word that describes the overly ornate, busy, ridiculously over-decorated, and garnished to the point of distaste.

the clothing looks ungapatchka.

Rococo is another term that might apply. Although more in reference to painting, it conveys the sense of gingerbread which this question addresses.

well i guess you could use the word bedeck.

for example my friend john led me to his room bedecked with green marbles

Shmonzes means valueless stuff--used for objects

small pieces of valueless decorative bric-a-brac; idle talk (Yiddish origin, jel.jewish-languages).

Schmates is for raggedy clothes.