this is why people get bit...

Something.everyone who has.a dog should
know or who doesn't have a dog for that matter, A WAGGING TAIL DOESNT ALWAYS MEAN Suten a ncedy nehaviour that tbey exhibit with In this video, the tail is very low, if you pair that with the slow moving dog and the low head and tense body, you get a nervous dog that's unsure.
If you then stroke at that point, they often tense up more and either back away and/or react which is what this dog has done, many times in If you then stroke at that point, they often tense
Don't be fooled by the paw either! That's a
learned behaviour with its owner that's becomne a habit, it's pushy behaviour but one that with a stranger can quickly go south.
With nervous dogs like this, wait until they have a calm body posture and stroke underneath.