@EvilPea Just to be clear, I'm not 'bleaching the grass'.
In general, I think people are getting the wrong end of the stick here - largely because I suspect there's a lot of pooing going on in gardens.
To clarify (and hopefully shut down the drive-by commentary), big dog normally goes for a poo on his daily walks - he has several a day. Some dogs poo on walks, it seems that some dogs don't. Both the dogs I've had have pooed on walks. Big dog, regular as clockwork, poos on his morning jog and on his last walk at night.
As such, big dog rarely poos in the garden. In fact, he rarely pees in the garden. This is partly because he is a complete Velcro dog and prefers to be underfoot of his humans than in the garden. It's also because I work from home and walk him anytime he barks at the front (or back) doors.
Due to the pandemic, my DH is wfh (I'm on maternity leave) and we are carefully following UK government guidance on social distancing. As such, we are taking it in turns to walk big dog twice a day - me going in the morning, DH in the evening.
My older DS is at home more than usual and playing in the garden. Big dog typically follows DS outside - it is, in fact, the only time big dog shows an interest in being outside (for everyone who's claimed that I'm being horrible to big dog if he's not constantly in the garden). Usually, if we open the back door to big dog, he just stands next to the door barking for us to join him.
Since my DH has been wfh, I have routinely found dog poo in the garden DESPITE the fact that big dog is pooing on his normal schedule, and DESPITE the fact that, as far as I'm aware, big dog has only been in the garden when older DS and DH have been in the garden. It is not a single poo. It is multiple piles - days old and covered in flies.
When this happened over the first weekend of lockdown, I got mad with DH who had taken DS into the garden while I dealt indoors with our nine-week-old-very-colicky younger DS. I couldn't understand how he could be in a garden that small, supervising a dog and a three-year-old DS, and not notice the dog pooing. He said that he would supervise big dog more closely.
This morning, I went to take out DS after the Easter long weekend and found, again, multiple piles of poo. Given I've never had a dog in ten years poo in the garden except when they had diarrhoea or sickness (and this was normal poo), I'm not used to dealing with poo and preschoolers in a small garden. I was particularly upset because my older DS had been playing in the garden in the area of the poo before I found it - he had run down the garden while I was manoeuvring the pram of my younger DS down the garden steps.
When I started the thread, I genuinely thought everyone's dog pointed/barked/sat at the back/front door and they took them out. I had no idea that dogs routinely pooed in their owner's gardens. I guess, as I'm self-employed and wfh normally, I'm in a privileged position of having an office dog who is either under my feet or we're popping down the road together for a walk.
So not crazy. Just somewhat cross at my DH. He has now, incidentally, said that he thinks the pooing is happening at night after I've gone to bed. As I can't just pop down the road anytime I want with big dog for the immediate future, we are going to try the tips suggested further up the thread. So, if big dog goes down to the end of the garden and starts sniffing (i.e. he wants a poo), I'm going to take him into the front garden and - if he won't go there - we'll go to a specific spot on the gravel that isn't where my DS usually plays in the back garden, treat, praise, and hope he gets the idea. DH is also going to try to take big dog for his evening walk earlier, in the hope that he won't poo in the garden in the dark.