zoid’s corollary:
[Police] + [appropriate ethnic group] = [good food] + [good price]
Police on a beat often cover the same areas day in and day out. They know where to get a good hot meal at a reasonable price.
If a Chinese (Mexican etc.) restaurant actually has Chinese (Mexican etc.) people eating in it you’re usually on to something good.
Silenus’s Addendum to Zoid’s Corollary:
[ethnic group 1] + [ethnic group 2] + [etc.] + [non-chain] + [weird decor] = [trancendant food]
Any place that gets all the racial and social groups in the area to eat at a place that looks like it’s been fire-bombed is a wonderful place to eat. It will probably serve BBQ, and you will love it! 
I’ve always avoided Hamburger Hamlet on the assumption (based upon cursory perusal while running past it at 10mph) that it was, as described, an “old peoples’ restaurant”. (Sorry, AARP crowd, but the label sticks.) I’m gratified to discover that my assessment was substantially correct. You should have just gone down to Wild Oats and gotten a sandwich at the deli. 
Stranger
Sometimes it’s location. One summer I waited tables at an Old People’s restaurant, and the food was good, reasonably priced, etc. My favorite group of regulars confessed they came so often primarily because it was familiar and pleasant, but also because they didn’t have to take the freeway and could even walk if they were feeling particularily spry.
Good one Zoid Police are often a good indecator of decent cheap grub.
And silenos has a good point, though maybe it can be simplified to two statements.
Silenos 1: Any place that looks like it has been firebombed and still has lots of customers is probably very good.
Silenos 2: Any place that is popular with multiple ethnicities is probably good.
Indiasia corollary: Any place where both far east Asians and Indians eat has got to be good.
One of the restaurants I eat at most often has a clientele entirely consisting of 1) sweet little twinks dining together, 2) very old men dining alone and reading the Journal de Montréal.
They have a big plate of eggs, ham, and hash browns for $4. It’s all good.
I’d refuse to go, too. That breaks my heart.
A friend went back home to Oklahoma to visit family. She offered to take her granddad out for lunch, her treat, anywhere he wanted to go. He picked the Luby’s. When they got there, he asked for a to-go box right away. As he ate his lunch, he’d take a bite, then put a bite in the to-go box. My friend couldn’t stand it anymore (had grandpa snapped? could he not afford food?), and asked him what he was doing. He said: “the lunch is too much food for me, but if I eat enough lunch until I’m full, then there isn’t enough left over for dinner, so I end up eating something else at dinner and gaining weight. But if I divide lunch evenly – one bite for lunch, one bite for dinner – then it all works out.”
Stranger: Wild Oats is out; my friend is on that whack-job no carbs thing right now. We can’t really go anywhere where there are carbs, because I fear for their safety.
I’m intrigued by the Bippy/Zoid/silenus principles of restaurant selection. Although you can’t really judge restaurant prices by cops, since many cops get the law enforcement discount wherever they go, which amounts to either half price or free. The other issue is that cops (the paranoid ones at least, which are the only ones I know) don’t like to go new places in uniform – they stick with the tried and true, because of fear that some saliva or something else will find its way into their food.
I love Golden Corral, but I learned never to go there at 8 pm on a weeknight (a good policy for all buffet restaurants).
I like Cracker Barrel also, as well as Bob Evans.
RE Hamburger Hamlet- I love that place! Hadn’t made it there for my past few visits to L.A. but I plan to make it there again. Also gotta go to the Hof’s Hut a couple blocks down from the Crystal Cathedral.
RE Buffets in the Los Angeles area- the QUEEN MARY SUNDAY BRUNCH!!! More food choices than I could even sample!!!
Btw, Hamburger Hamlet’s FRENCH ONION SOUP WITH THE MOZARELLA TOPPING!!!
What the “old people” means depends on where they come from. Many “old people” in the US will eat many things that I would say have anything, flavor or not. Most (I think) Thai old people would prefer something very tasty (lots of spice, many flavors). In the US, I fear elders prefer bland food. I may be wrong.
Does Ponderosa count as an old people’s restaurant? If so, sign me up-I love the all you can eat sundae bar!
To a teenager 30 is old.
This thread lacks context.
Sometimes there are plenty of trucks parked outside simply because the place has plenty of truck parking.
One of the best dining experiences I ever had happened completely outside of my control.
I had to attend a meeting in The City At The Bottom Of The River with a bunch of other engineers and one of them happened to be second-generation Chinese-American.
When dinner time rolled around she took us to this place in Chinatown. It was off an alley, and there was no sign or anything, but just another door in all ways unremarkable.
We went down a dingy stairwell into a basement, and there was a beautiful restaurant in there, absolutely packed with people (I’m assuming Cantonese, but that’s just a guess). Nobody spoke any English, so our guide ordered a bunch of stuff and we ate family-style while I embarassed myself trying to manipulate chopsticks in public.
I haven’t had better food since.