A word to make something bad sound good

Talking it up. Dressing it up. Putting it in a good light.

Sugarcoating is one possibility -- if the book is "sugar-coating" teenage drinking, it is taking something negative and adding a superficial positive sheen. Merriam-Webster:

to talk about or describe (something) in a way that makes it seem more pleasant or acceptable than it is

Glamorizing is another -- to glamorize is to take something that is neutral, or maybe negative, and imbue it with more of a glamorous aspect than it might deserve. Oxford:

Make (something) seem glamorous or desirable, especially spuriously so

I think either of the above would convey your meaning in this context.

Here are some possibilities:

• justifying
• excusing
• promoting
• rationalizing
• papering over
• glossing over
• condoning
• whitewashing

I think whitewashing is probably the best choice.

I don't believe a single word would capture what you are describing. Languages don't usually work that way. It is neither necessary nor desirable to try to condense every concept into a single term. From what you say, the book is doing nothing to teen drinking. It simply omits any description of the dangers.

Destigmatize might be the word you are looking for. Opposite of stigmatize. "destigmatize violence" returns about 700 results in Google.

destigmatize: to remove associations of shame or disgrace from
Merriam-Webster

not mentioned yet:

• exalting
• extenuating
• palliating

neutral:

• describing
• portraying
• depicting

neologisms and creative solutions:

• innocenting
• naivizing / naivicing / naivising, naiving
• anglizing / anglising / anglicing – antonym to demonizing, not to be confused with anglicizing)
• depuritanizing or repurposed purifying
• evangelizing – if it’s close to promoting
• subliming – ditto
• madmenning > madboying, madkidding, madyouthing – pop culture reference, to expire soon
• deconsequencing, asequencing, nonsequencing … – leaving out consequences
• roseglassing – as in through rose-colored glasses
• unicorning, rainbowing – similar to sugar-coating
• stonering – as in stoner movies
• targetdemographicing
• politicianizing – make sound or appear politically correct
• spindoctoring or repurposed spinning or doctoring
• truthbending
• ebaying, fleamarketing

In addition to the upvoted answers (I often hear “glorify” used this way in AmE, possibly due to the Hays Code), I’d like to add the concepts of sympathetic portrayal and sentimentalization.

---

You could say that the book cast underage drinking in a sympathetic light or that the book offered a sympathetic portrayal of teenage alcohol consumption.

sym·pa·thet·ic
adjective

: having or showing support for or approval of something

: having pleasant or appealing qualities : causing feelings of sympathy

[. . .]

5. a : showing empathy

   b : arousing sympathy or compassion
   a sympathetic role in the play

_{Source: Merriam-Webster definition of “sympathetic”}

---

“Sentimentalization” is not particularly apt for your specific case, but might be useful to others with a similar question.

sentimentalize
[transitive, intransitive]
sentimentalize (something)
(disapproving)

to present something in an emotional way, emphasizing its good aspects and not mentioning its bad aspects

Jackie was careful not to sentimentalize country life.

_{Source: Definition of “sentimentalize” from the Oxford Advanced Learner's Dictionary}

Euphemism: A mild or pleasant word or phrase that is used instead of one that is unpleasant or offensive. (from "Merriam Webster")

bib's suggestion of glorify, and McGarnagle's glamourise are obviously superb.

Below are a few others words that - at least in one of their meanings - specifically convey undeserved or excessive praise. All definitions/links from http://www.oxforddictionaries.com. Example sentences mine....

• aggrandise: enhance the reputation of (someone) beyond what is justified by the facts - "the book aggrandised the reckless, wanton behaviour"
• dignifies: Give an impressive name to (someone or something unworthy of it) - "the book dignifies drunkenness as some manifestation of personal freedoms"
• idealise: Regard or represent as perfect or better than in reality

And another that isn't necessarily unwarranted praise, but would imply that pretty clearly if describing such a book:

• poeticise: to give a poetic quality to

If you want a fancy word for it, I suggest edulcorate.

Edulcorate: Make (something) more acceptable or palatable

Example: The traditional folk song is today often edulcorated by unwarranted accompaniments.

[Lexico]