Are consumer-grade thermal imaging cameras any good for spotting heat leaks in a house?

That’s my understanding too. I’ve heard good things in the trade about Testo cameras - and cheaper than Flir etc

If you’re interested in heat loss think about calculating loss with an app. Www.heat-engineer.com offer a £10 service - many pro engineers are now using it. I had a look at it a while ago and seemed relatively easy to use as apparently pretty accurate if you understand how your house is constructed