This simply isn't true. There are a few who did that, but they're the exception, not the rule.
Shady unicorns: Uber (too many to count), AirBNB (spam), DropBox (lied about encryption/security), The Honest Co (lied about product quality)
Not Shady unicorns: Xiaomi, Palantir, Snapchat, SpaceX, Pinterest, Spotify, DJI, Intarcia, Stripe, Vice, CreditKarma, CloudFlare, BloomEnergy, Fanatics, Slack, Blue Apron, GitHub, Domo, SurveyMonkey, BlaBlaCar, Lyft, MongoDB, Buzzfeed, Cloudera, Automatic, EventBrite, Evernote, Warby Parker, Docker...
The narrative that "everybody cheats" is just something that cheaters tell themselves, so they can pretend that their behavior was warranted.
That said, it's worth discussing these things before applying to a company, because dishonesty creates massive risk in the company, so if you hear and answer that sounds like 'downandout's, you need to devalue that company, because their lack of ethics creates risk for that particular company, and it creates reputational risk for you.
Xiaomi sent user data to China without consent. [1]
Palantir proposed an illegal campaign agaisnt Wikileaks [2] and its very industry is by its nature fairly dubious and shady, though that doesn't mean it's doing things that are strictly illegal aside from what is known.
Snapchat ignored and didn't fix various privacy and security issues. [3]
Pintrest operates in a dubious copyright gray area. [4]
Spotify pays artists very little and most money gets sent to record labels. Even labels see almost nothing. [5]
Like Uber, Lyft engages in unethical treatment of its workers. [6]
I can go on. The badness of these things varies significantly. Not all of them indicate a company is totally unethical. But I think the assertion "most Silicon Valley companies are doing at least some illegal, scammy, or otherwise unethical things in order to get ahead" is completely true.
[1] http://www.zdnet.com/article/xiaomi-under-investigation-for-...
[2] http://www.forbes.com/sites/andygreenberg/2011/02/11/palanti...
[3] http://www.nytimes.com/2014/11/27/style/uber-facebook-and-ot...
[4] http://www.businessinsider.com/pinterest-illegal-faq-2012-2?...
[5] http://www.hearya.com/2012/11/28/david-macias-enlightening-l...
[6] https://www.reddit.com/r/Lyft/comments/2y16r3/lyfts_highly_u... (aggregates news articles)
How is that shady? They have deals with the appropriate companies.
Buzzfeed spams the crap out of Facebook. Eventbrite & Vice had some spamming issues in the beginning as well. I'm not sure about Snapchat's growth story - they may have been a rare example of natural growth, along with Google. Most of the rest of those you're talking about aren't really the kinds of pure internet plays that are relevant to this discussion. No amount of spamming would have made Xiaomi, Palantir, SpaceX, DJI, etc any more successful, so they didn't employ these techniques.
AirBNB's CAN-SPAM violating email was clearly unethical. A media company showing up on Facebook more than you would prefer is, at worst, mildly annoying. There's an important difference.
Ethical people do not need to leave Silicon Valley. Dishonesty is not prerequisite to success. Your claims are wrong.
Again, you're implying things that I simply didn't say.
>A media company showing up on Facebook more than you would prefer is, at worst, mildly annoying
You're right, that's not spam, but that's not what I was referring to either. I'm not going to write a massive explanation here of the specific Facebook spamming techniques employed by Buzzfeed et al, but suffice it to say that they are actively and aggressively spamming to "prime the viral pump" with certain stories.
This is a stretch.
However, I decided it was ethical for the context of this conversation, because to my knowledge they don't lie to grow revenue. They claim they'll charge a huge pile of money to analyze data, and that's precisely what they do.
Almost every company is mendacious and shady.
Good God!!!
Google's growth was organic and based on a very high quality search product. The spammier search engines all basically died off.
So I disagree with your premise that Silicon Valley success is generally based on spammy or unethical behaviors. Yes there is way too much of it, but no, it's not a necessary part of success.
Is spamming/other bad behavior "necessary" for Internet success? That's an interesting question. I can only think of a small handful of successful Internet companies that magically went viral without such aggressive "growth hacking". The overwhelming evidence is that "necessary" may be a strong word, but "highly unlikely without it" is probably an accurate description.
This could be the story of literally any large tech company today. Airbnb got its start by spamming people offering vacation homes for rent on Craigslist [1]. According to The Facebook Effect [2], Facebook was almost entirely dependent on its contact importer/spammer for its growth in its early days. On days when Hotmail blocked them for spamming, new user sign ups dropped by 80%; it was only after they cut a deal with Microsoft that included an agreement to not spam-box their emails that they continued to grow.
When you look behind the curtain of successful modern startups, virtually all of them were built on mountains of spam and bad/unethical/illegal behavior, which they then publicly decry and block on their own platforms after they become influential enough to do so. If you have issues with this, Silicon Valley probably isn't the place for you. There are plenty of tech jobs in other areas - but look away from startups, because most are employing/willing to employ extremely aggressive techniques to win.
[1] http://davegooden.com/2011/05/how-airbnb-became-a-billion-do...
[2] https://en.m.wikipedia.org/wiki/The_Facebook_Effect