So here's some tips for dealing with it:
1. Know Your Audience
There seems to be two sides to this unappealing sandwich: either Person A -the overly-hypersensative type- posts up on how they're tired of dealing with issues that only make up < 5% of the site's content...
or Person B -who doesn't value anyone else's opinion- who posts content saying "just having fun", "haters gonna hate", etc.
Don't share their opinions and don't feed them! Both will perpetuate the issues even further.
People fail to understand that car modifying is subjective, on a personal (in every sense of the word) and public level. On one hand, how you modify the car reflects on you as a person. People are allowed to be extremely critical because you bought cheap parts and everyone told you not to paint your wheels tiffany blue, but you did it anyway, stupid -- no one forced you into it and no one cares how easy it can be undone.
In the same respect, don't cling to the idea that "I build for me", or "at the end of the day it doesn't matter what people think as long as I'm happy with it." False. If they didn't care they wouldn't be posting their content on sites that give you likes or appraisal.
We have to acknowledge the very public nature of this hobby, rather than hide behind silly individualistic notions. However, we also have to take into account that the majority of the cars that get attention are wildly impractical, so a happy medium between the two seems to work best.
2. Ask Questions Prior to Making Purchases
Countless, countless times I run into people who made purchases on a whim; albeit cars or car parts. Instead of asking me: "I have (this much money) and I want (this) - what do I do?", I get: "my shit broke. How do I fix it?", or "why doesn't this work?".
The best advice I can give anyone in relation to a hobby is this: before you make any purchase, find the biggest nerd or someone who gets it and befriend them. Odds are they'll be an asshole, but they've spent years studying, critiquing and rebuilding their things -- and if you express interest in their opinion they'll steer you in the right direction. It's that simple. It's the reason I've come so far with my projects.
3. Don't Sell Anything
Seriously. It's a complete waste of time unless it's through eBay or Craigslist or any marketplace where people can't express their opinions. You can get one word wrong and find yourself dealing with a shitstorm over nothing more than semantics. Be detailed, but don't seem eager. Car people don't have money.
4. Choose Your Battles
I don't need convincing that a roof rack, cargo attachment and LED light bar looks good on a bagged sedan. It doesn't. But I'll gladly question the impracticality of aesthetic choices (cause that's all it is) any day. I also have to be prepared to take criticism and I often times forget.
Seriously, other than the MPG loss and the urge to validate your active lifestyle, why would you need that?
If I had a dime for every time someone told me to get bigger wheels...
I tell them, the wheels are discontinued; rare, and were designed by a quality manufacturer specifically for my car, so no.
I literally had to go through the effort of factoring in that conversation before I purchased my wheels; taking the time to consider all plausible hypothetical arguments -- that's something to think about. Remember, we make the decisions to purchase shoddy or quality parts (regardless of budget (you're modifying a car, it's automatically a luxury expense)). And regardless, there's battles we can't win, but we can plan ahead by double checking intentions before throwing it out for everyone to see.
5. Avoid Old Rhetoric
Your stock 95 Honda Accord shouldn't plug anything "illest" and neither should you. Some people call it art, but the ones selling it are more interested in making money off you then they are your original sense of style (to which a lot of people have the exact same original sense of style, apparently). Taking yourself seriously goes a long way. Have fun with it but be prepared to defend yourself from d-bags like me.
6. Be a Good Critic
The worst kind of person is someone who is cynical and hopes to gain nothing by it. You don't have to chariot in on a white horse to be someone's dickery-savior, nor should you go around looking to argue, either. Recognize faults and offer ways to improve, not simply inform. Also, you don't have to like everything you see, but if you only care about the content that directly relates to you, you're stifling yourself.