You had one job
Should I need more they're the cheapest way to buy an ESP8266 module, especially with through-hole connections.
They're also very compact. The flipside of this is they only have a couple of conventionally usable GPIO pins and are a pain to work with in other ways. You can't use them in a protoboard because of the double row connector layout. You also need to pull several pins high for them to boot up, change that for programming and so on.
Which is why I've got a load of ESP-01S modules kicking around, I now use WeMos D1 mini boards most of the time I want to use use an ESP8266 in something.
With a view to using this stash of components up I bought these little special purpose USB-Serial "ESP-01S link" adaptors.
Which didn't work.
I was surprised as the stuff I get from Banggood is almost without exception good, I don't think I've ever had anything completely duff from them apart from this.
A bit of poking around showed they don't pull the CH_PD pin high, which is needed for the ESP-01S to boot. So I've soldered a little link on the bottom (see picture) and now they're perfect. With a button and a couple of more links they could be configured for programming the ESP-01S but I'm not fussed about that. I want these as diagnostic tools.
I've written some minimal code that lets you use one as a 'bridge' to painlessMesh over a USB serial port. It prints any incoming packets from the mesh in a simple text format and you can send unicast or broadcast packets. An ESP-01S in one of these adaptors makes for a nice tidy little 'dongle' to work with.
I might cook up a simple UI to get a list of nodes, topology and so on, but this is all I need for now.