Sorry if this sounds strange, but do any of you ever have clients who don't cum? I was giving a hand job to a punter last night and he didn't ejaculate, even though he seemed to be enjoying what I was doing. He was an older guy so maybe that has something to do with it. Is this quite common? I was thinking I should improve my technique but my other punters always cum, so it could just be him...

Yes it's not uncommon for men to not cum, just as I'm sure all women don't always climax. If it's with someone new I'll often ask about it, sometimes it's nerves, medication, delaying until the point where he can't, lots of reasons.

At some point most, if not all of us guys will experience one or all of the following . I know I have.
1) can't get hard
2) can get hard but can't stay hard
3) cum too quickly
4) can't cum at all or would take what feels like days.

Can be many reasons for all of the above happening.  But I would say that every one of them are perfectly normal to experience at some point. If they always happen then need to explore for reasons.
I always find most are stress related and disappear when you are comfortable with someone, more relaxed you are the less you are thinking about the sex and actually just enjoying it.
Just make sure the punter is relaxed and give him the space to be able to mention what he is happy with. Most eventually will be happy to say if they are experiencing any of the above.

My 50 year old ex rarely orgasmed, it was hell there is no denying. Just going on and on and on I love sex but ran out of excuses in the end. I could not face of another one hour session of feeling like I was trying to milk a cow, i would have sympathy for him but he was a massive bell about it and would make me feel it was my fault. Little did he know I make men cum for a living!

Delayed ejaculation is usually psychological, but also can come from men watching too much porn and wanking in a way that a vagina can never compete with, or using toys that vibrate especially prostate massagers and well as some other health reasons.

It happens. Doesn't matter about age either. I've had a young guy who couldn't cum. He'd had a pre-wank not long before we met as he was excited and couldn't wait.
I have a guy in his 40's who doesn't always cum for various reasons.
Then there's the guy who wanted oral for an hour and he told me during initial comms he wouldn't be cuming.

Yea it's weird when they don't. But after having a chat everything is fine. They are happy without the 'happy ending' and sometimes it's just nerves like the one in his 40's. Now he knows me a bit more, he finds it easier to cum.

The guys that can only cum when wanking I find that at this point they insist on doing it themselves whilst I do whatever they request.

Chocks I used to feel really embarassed too because I felt too responsible for their bodies. If guys are over-wank their penis becomes physically insensitive, and it's less and less likely to happen. I have this 7 minute rule. If it's not happening after 7 mins I  give them the 'exciting option' of wanking themselves while I watch 'entralled'. I make it sound very nawty.

If they play dumb I place their hand on their cock to encourage them to wank and they either cum in 3 minutes or sheepishly admitted it's a dead dodo. This works nice for 90%. Another option is I ask if they'd like to be left alone to sort themselves out and I come back in 3 minutes. Some prefer that as they have no distractions.You can play that a few ways.

I generally give them 2-3 gentle, good humoured hints and guidance but if all the above fail,  I say 'I bet your going to cum like crazy when you get home tonight...wow! time flies doesn't it? it's end of the session!' That's the quickest 'man cummer'.

I know what you mean when there's zero feedback or facial paralysis it's a bitch and pretty freaking spooky. We won't generally know the reasons. Actually we don't need to. Just be upfront and cheerful while sticking to your toolbox of strategies and timings in your head!

I think most silent ones are game playing...for whatever reason and I just game play them back in a lovely, charming, giggly way.

He's a good guy Charm! The ones who tell you they have medical or physical issues are our best friend.