I want to go so bad or badly

I got a dilemma with choosing the right form in a sentence.

1. I wanted it so badly (we can often hear in everyday conversation)
It seems to me that this is grammatically correct as we use an adverb and we answer the question: How badly did you want it?

2. Then I typed: I screwed up so badinto google and amazingly got many entries.
Can someone tell me where's the difference? Is #2 more colloquial?

Badly is an adverb and correct grammatically.

Bad is an adjective and although it is in common use it's wrong.

Badly is an adverb and correct grammatically.

Bad is an adjective and although it is in common use it's wrong.

Yes, but why do people use "bad" sometimes and I mean native speakers.

I got a dilemma with choosing the right form in a sentence.

1. I wanted it so badly (we can often hear in everyday conversation)
It seems to me that this is grammatically correct as we use an adverb and we answer the question: How badly did you want it?

2. Then I typed: I screwed up so badinto google and amazingly got many entries.
Can someone tell me where's the difference? Is #2 more colloquial?

The only difference is that 'bad' as an adverb is nonstandard. Nonstandard does not mean incorrect or wrong. That's an incorrect assumption to make.

Casual speech often uses certain "adjective" forms as adverbs.

Results 1 - 10 of about 12,400 English pages for "wants it badly".

Results 1 - 10 of about 42,100 English pages for "wants it bad".

Results 1 - 10 of about 295,000 English pages for "want it bad".

Results 1 - 10 of about 144,000 English pages for "want it badly".

M-W:

Main Entry:
3bad
Function:
adverb
Date:
1681

: badly <not doing so bad> <doesn't want it bad enough>

Encarta:
adverb
Definition:

1. badly: in an unsatisfactory manner
We didn't do too bad.

2. very much: to an intense or extreme degree
He's got it bad!

[13th century. Perhaps < Old English bǣddel "effeminate man"]

I have a dilemma...

Why are you learning English? If it is to chat on the Internet, then yes, grammar becomes irrelevant, and you need only the highly restricted vocabulary of an 8 year old. You will not be required to articulate thoughts and feelings, other than to say you think something is 'kewl', 'awesome' or 'it sucks'.
However, if you are wishing to advance yourself in a career - and particularly in business, science, education, or the hospitality industry - you will have little credibility with any prospective employer - nor much respect from those with whom you would come into contact!
Having said that, native speaks often relax grammatical rules, and might even speak ungrammatically for effect. You have picked up the important distinction, Besthost, which is knowing what is the correct grammar in a sentence', and then noting when native speakers relax the rules. If in doubt, always use correct grammar.

I have a dilemma...

Why are you learning English? If it is to chat on the internet, then yes, grammar becomes irrelevant, and you need only the highly restricted vocabulary of an 8 year old. You will not be required to articulate thoughts and feelings other than to say, 'kewl', 'awesome' and 'it sucks'.
However, if you are wishing to advance yourself in a career - and particular in business, science, education, or the hospitality trade - you will have little credance with any future employer.

You do indeed have a dilemma, David. You seem to have a terribly skewed idea of what constitutes grammar. It doesn't at all resemble that of language science.

Why should ESLs be satisfied with simplistic responses like, "It's wrong/incorrect. You should/must do this and that". How could answers like these help them function successfully in all the social registers of English?

The Cambridge Grammar of the English Language

The aspects of some prescriptive works that we have discussed illustrate ways in which those works let their users down. Where being ungrammatical is confused with merely being informal there is a danger that the student of English will not be taught how to speak in a normal informal way, but will sound stilted and unnatural, like an inexpert reader reading something out of a book.