They certainly scan every bag, at least at every airport I've been to. As
@koraks says you can often glance at the screen. What they won't tell you usually is what all the colours on the screen mean. Sometimes suspicion is aroused by SLR lenses, I believe due to all the glass. Anything that arouses suspicion is likely to result in a second scan at increased intensity, or a hand inspection of your bag. Which is why the lead lined film bags are often bad news, they just zap harder.
The latest new CT scanner is quite compact and could be mistaken for a regular X-ray scanner. That's a concern. We do need the various airport authorities to agree on how to handle photo film.
Currently in the USA, hand inspection has been permitted for a long time and it seems quite normal for hand inspection requests to be granted for any reason including film. Several reports, including my own from 13 months ago, paint a picture of at least major US airports including in their signage whether the scanners are film safe, and what to do with film. This is excellent and shows they have noticed.
In the UK, civil airports are under the umbrella of the Department for Transport which has listened to Kodak and Ilford and issued instructions to all passenger airports to accept requests for hand inspection of film where CT scanners are installed. The trick is knowing this. It's not publicised.
Other popular destinations such as the EU, Japan, Australia don't seem to have done anything yet. Didn't we have a report about a couple of Middle East airports basically not knowing about film?
In the UK, there is a gradual move towards all airports replacing the older regular X-ray scanners with the CT scanners. For 95% of travellers this will be positive because they'll no longer have to worry about baggies of liquids or taking electronics out. The electronics rule in particular is different at just about every airport and sometimes at the whim of the security staff. CT scanners will remove that inconvenience and uncertainty for the vast majority. But with just a little effort on the part of those responsible for airport security, things can be made safe for film too.