For many years I frequented the Sala Thai on P Street in Dupont. In the last couple of years, its quality has degraded markedly -- particularly in its take out / delivery food. I recently had to throw out barely eaten a delivery order from that place (something I have never done before, from any restaurant). The beef was the most foul beef I have ever seen: sickeningly stringy / fatty, tough, and alternately overcooked and undercooked. The pork appeared similar in substance to sushi. This was the most disgusting meal I have ever been served. I am hugely disappointed as this place was once quite good.
It wouldn't surprise me if the quality of its dine in food is much better than its take out / delivery. I don't think there is any chance they would have served what they gave me to a customer dining in their establishment (i.e., that they had to face in person). This raises an interesting issue. I have often had occasion to surmise that restaurants -- particularly asian restaurants -- seem to serve markedly inferior food to take out/delivery customers than to dine in customers, both in terms of quality of ingredients and preparation. I have often had bad take out from a place that serves consistently good dine in.
In any case, I would strongly advise everyone to avoid Sala Thai's P street location, at the least for take out / delivery.