You don't hear about things gunking up the gas tank as much now as you used to. When's the last time you remember worrying about trash clogging up the filter? If your answer is not lately, then that's because technology has evolved in cars just like it has in everything else. If your answer is yesterday, you might want to stop driving around your grandmother's oldie.
Mesh to Let Gas In
While it is possible for things to get stuck down there and mess up your filter, it's probably not going to happen in your normal day-to-day life. There's a mesh in there designed to let the gas in, but not anything solid. As long as you aren't running around all day every day with your gas cap off, it's pretty unlikely that you'll get enough stuff in there to cause any serious, or even minor, problems.
Of course, that's only if everything is in working order. If your fuel filter isn't working quite right, then something that might not have been a problem can become a very big one. It's a bit of the car that tends to not get as much love as other parts. But that doesn't mean you shouldn't worry about it; quite the contrary. Replacing your fuel filter regularly is an important part of keeping your car up and running in good condition.
Bad Mileage is a Sign
The first sign that something may be wrong with your fuel filter is something that's pretty easy to overlook or mistake for something else; bad mileage. If it's left without replacement or repair, then you could be looking at more serious problems. In the worst case scenario, it could cause the engine to completely stall.
So, you don't generally have to worry about anything getting into your fuel tank and clogging it up. But that doesn't mean that the fuel tank isn't something to worry about. Replacing it every 50,000 miles is advised, at least. Depending on what you're running, you might want to replace it a bit more often than that.