The sonnet is an endless descent into hell.

No, I hardly agree with a word of what you have said here! This is the whole sonnet, so we can see it in context.

‘Tis better to be vile than vile esteem'd,
When not to be receives reproach of being,
And the just pleasure lost which is so deem'd
Not by our feeling but by others' seeing:
For why should others false adulterate eyes
Give salutation to my sportive blood?
Or on my frailties why are frailer spies,
Which in their wills count bad what I think good?
No, I am that I am, and they that level
At my abuses reckon up their own:
I may be straight, though they themselves be bevel;
By their rank thoughts my deeds must not be shown;
Unless this general evil they maintain,
All men are bad, and in their badness reign.

http://etext.lib.virginia.edu/toc/modeng/public/MobSons.html


Here is my gloss on the poem’s argument:
If you are going to be falsely accused (“esteem’d”) of being vile it is better to actually be vile, since at least you are then ‘true’, and will have enjoyed a pleasure that is actually “just” despite the fact that it is named vile by the mob (“so deem’d”). (lines 1-4)
For why should my natural sportive actions be coloured by the judgement of “false adulterate eyes” who assume I behave as do they, or why should my imperfections be gauged by even poorer people’s standards, whose morals are different to mine? (lines 5-8)
No, I am true to my own beliefs, and those that judge me otherwise are simply reflecting their own warped natures: I am straight to their bent, and my deeds must not be judged by their corrupt imaginings – (lines 9-12)
Unless this vicious generalisation is held to be true: Mankind’s nature is inherently evil and thus our natural actions are perforce evil too. (lines 13-14)

This is, I would suggest, an incredibly modern poem in its outlook. Its insistence on a kind of personal truth is one we may fondly imagine to have been invented in the 20th C – yet here is a poet (pre-dating the foundation of America, Australia, New Zealand, South Africa) saying “follow your natural instincts, these can’t be wrong unless you believe our basic nature to be evil; and disregard what the vicious mob might say about your actions because it is more important to be true to yourself!” Note he is saying it in a sinuous poem of 14 lines that harks back to classical forms and classical rhetoric – note the choice of an obvious Latinate word, not ‘greet’ but salutation, and the closure with a couplet perfectly encapsulating the idea of reductio ad absurdum..

In short, far from being a descent into hell it is an uplifting account of what the human spirit can be.

YART alert!
BTW, if anyone new wants a steer towards World Wide Will, try some of these resources:

Complete Works:
http://tech-two.mit.edu/Shakespeare/

Complete guide to Shakespearian resources on the net:
(one of the best literary sites in the world – has both good content and excellent researched and annotated meta-search functions)
http://daphne.palomar.edu/Shakespeare/

Basic guide to scansion of the poetry:
http://sterling.holycross.edu/departments/theatre/projects/isp/measure/teachguide/scansion.html

Index (Library of Congress) of Shakespeare on film:
http://lcweb.loc.gov/rr/mopic/willfilm.html

Good text access:
http://etext.virginia.edu/shakespeare/works/

SUPERB general look up resource for anything academic:
http://www.boxmind.com/default.asp
(it beats the hell out of a plain vanilla google for this type of searching, IMO.)