I've seen this a lot, and I'm sure others have too. You go to the lake/dock/river/sound/whatever and there they are:
1.) The guys who only have 'one' salmon, though you've seen them take at least 3 to a cooler in their car.
2.) The guy who's fishing with 3 poles in the water.
3.) The guy who catches one rockfish when the limit is one, and then says maybe he'll come back later.
I saw a lot of #1 when I was fishing for fall silvers several years ago off Dash Point pier. It got to the point where I was fishing one day and caught my limit of two, and the kid next to me asked why I was packing up to leave, and when I answered I had my limit and was going home, he said "Why don't you just go put them in your car so you can fish more?" What kind of lesson does this teach to kids, to flaunt the regulations and take more than your fair share?

I didn't call the warden, but it really rankled me, and I've always regretted not doing anything about it, especially since it went on for weeks and weeks, and some guys down there would show up every day and fish all day, and keep every fish they caught.
I was at Des Moines pier today, and saw #3. I didn't say anything that time.
Then I went to Lake Fenwick, and saw #2. I pointedly asked the guy, "You know you can only fish with one line at a time, right?" And he said, "I know." But that didn't stop him from casting two lines out at once. After about 45 minutes, I just couldn't stand it anymore (especially since I saw him rebait both lines several times, and one of his lines in the water was always right across where I wanted to fish), and left to call the WDFW poaching hotline. I didn't stick around to see if the warden showed up, but I'm hoping she did. Now, I would love to fish with 2 rods myself, and I was hoping that regulation amendment would pass and allow us to use more than one, but it didn't.
Dammit, I follow the rules, but it seems like sometimes I'm one of the only ones. I never know what to say to these people.