Street food anxiety keeps a lot of budget travelers eating at overpriced, blander restaurants when the best and cheapest meal of the day is usually one stall away. A few real signals reliably separate good stalls from risky ones.
The single best predictor: a line of locals
A stall with a steady line of local customers, especially at a normal meal time rather than off-peak, is turning over food fast enough that nothing sits around. This one signal outperforms almost any other visible cue.
Watch how food is held, not just how it's cooked
Freshly cooked-to-order food (grilled, fried, or wok-tossed in front of you) is generally lower risk than pre-made dishes sitting out at room temperature for an unknown length of time, even if both look identical on a plate.
Ice and water are the more common actual risk
Contaminated water is a more frequent cause of travelers' stomach issues than food itself in many destinations. Skip ice unless you know it comes from a sealed, purified source, and stick to bottled or filtered water, including for brushing teeth in higher-risk areas.
Takeaway: Follow the line of local customers, prefer food cooked fresh in front of you, and treat unknown ice and water as the bigger risk than the food itself.