Reddit

Depends on the subreddit. Some are informative, some are just circlejerks. I use it to get the news without the annoying ads.
 
I'm experiencing a problem with an online store and want to warn others. Is Reddit the best way to get the word out?
 
im on it. its boring tho. 99% of it is cute kitty and cute puppy gifs...

Then modify your default subscriptions, and set up some multi-reddits. Change the defaults to make the main page not suck, then use multi-reddits to group your interests. I have a lot of obscure hobbies and reddit is great for that. /r/Toronto is also pretty good for knowing what's going on in the city. Otherwise it's basically an information aggregator that lets you discuss things, and how good that is largely depends on what you see.
 
Yes, but how do I warn other people that a local online store is acting unethically and probably illegally?

If it's an online store why not mention that in online reviews of the store? You could write an article in /r/Toronto and it would get seen (local media lurks there), but maybe ask /r/askTO first if you aren't an active Redditor.
 
What are /r/Toronto and /r/askTO? How do I post there?

Reddit is divided into subreddits, each having their own rules and moderators. /r/Toronto is for toronto based things, but not questions. /r/askTO is for questions about Toronto. So wondering if a post is appropriate for /r/Toronto is a question you could ask on /r/askTO. How do you post? Sign up and post.

Also, /r/gonewild is amateur nudes. I'm not subscribed but I do browse...