But what if your character admits that they hate republicans, or uses the name of a certain celebrity as an example for a person he thinks is stupid? What if your antagonist is a member of an actual terrorist organization or expresses ideas that sound pretty darn similar to a politician who appeared in the news recently? Is there ever a point where modern fiction becomes just too real?
In most cases, it's a matter of intent. What do you gain by specifically using one company or brand or event in your writing? Is it for the instant recognition of the name? To make characterization easier? Maybe your character's tastes are so distinct that saying anything but Cheetos makes it hard to stress your point. But what does your story gain by taking a dig at that certain celebrity? Are you trying to express your character's biases...or your own?
Although a lot of us read fiction specifically because it's not real life, reality will inevitably creep into fiction, and that's okay. Some writers use their writing to poke fun at real life, or point out societal problems that need to be addressed. Others write to explore elements they wish they could find in reality, like magic, mystical creatures, and superpowers. Sometimes these two segments will mix, until you can't really distinguish one from the other. But it's important for writers to be aware of their own preferences and opinions to help prevent alienating any one group. After all, you want your work to reach the largest audience possible, something you won't likely achieve by pissing people off.
At the same time, you can't please everyone, and sometimes there's no ulterior motive on the part of the author. Maybe you're actually quite conservative yourself, but find it interesting to explore a viewpoint on the other side of the spectrum for your novel. And if it's fiction, which is by nature fabricated, surely there's no problem in taking some subtle digs at that certain person from that show who you really can't stand...?
- Using trademarks in fiction is not wrong, per se, but contrary to what you may think, the company would prefer that you don't use them: instead, use the generic terms. Why? Because when trademarks become so common in everyday language that people use them to apply to a whole segment of products, then the company can actually lose their rights to the name. Think of words like yo-yo, which used to refer to only one brand of yo-yo but now applies to all yo-yos. The word is so commonplace, I can't even think of a synonym for it. That's what companies are afraid of. You can't make a profit off of branding if just anyone can use it.
No, you're probably not going to get sued by a company for using their name in a novel, but it could happen. As a general rule, avoid using trademarks unless absolutely necessary. Making up your own company name is also an option.
- Politicians and other celebrities generally don't have trademarks on their own names (last time I checked), but their names are still considered a brand in some ways. After all, they're depending on the instant recognition of their names to help sell an idea or a product. But then there's libel, or defamatory written statements, which you still can get in trouble for.
(Obviously, mentioning real-life terrorists by name is sketchy if you value your life.)
Bottom line: It's wiser (and safer) to depend on your own words to get your point across - not someone else's.