We have a homeless hostel next door and the caretakers have a staffie/bulldog type of pup.
Now bearing in mind this man boasts about his pittbulls at home in Poland, my OH has just heard him goading and baiting the pup  until it was growling, spitting and totally hyper. He was then praising it. This was def not just a case of rough play. My oh knows the difference.
I wouldnt be surprised if he set it on my dogs as we do not get on and I want to prevent this and stop him mistreating this poor tyke.
It looks well cared for other than this.
Would a sound tape help as we cant see into their gdn without them seeing us so we cant tape a video.
Who do I contact and what can I do to stop this?

this is awful but i don't really know what to do either.
Have you tried ringing the RSPCA for some advice, they may well be able to tell you the right people to contact. i expect they will say the police but if the pup is well looked after and in good condition then proving there is anything wrong would be hard to do.
i would try videoing them if you have a camera but be careful else you may be the one in trouble with the police.
Let us know what happens.

Ive spoken about this on another forum too and have been advised to contact the police/dog warden/rescues/sspca/dog aid. Trouble is I think the police may think we just want rid of them but we are going to tape them. We cant video them without being seen but we can tape the noise so we will do that and see where to go from there.
It is worrying when this man, covered in tattos, boasting about having pittbulls back in Poland, is the type to breed her, use her to frighten the homelss residents, many of whom are very vulnerable, and possibly try to attack my dogs.
I will listen for him doing it again tonight and every night until we have enough evidence.
The man next door on the other side has heard it too but does not want to get involved as he is scared of that man and his gf so I guess our love of dogs will see us thr this

You say this is a homeless hostel? So, wouldn't the council be interested in what is going on? I find our dog warden very helpful.

As well as filming the sounds i would start noting down what time it happens each day, what you can see him doing to this dog, how long it goes on for etc. If there is a pattern to this maybe then someone can come and visit in a plain car from which ever agency to witness this for themselves from your place.

Is this a private run homeless shelter or this man the manager for an agent or YMCA? If run by the council or other organization i feel that they would be interested in this, but i would say start gathering as much evidence as possible. Can you see whats going on from an upstairs window, maybe be crafty and film him with the dog this way through a blind or partly open curtain? But i would say be very careful on this front as you don't want him to witness you doing this, as this could cause you more problems and make him go underground with what he is doing, then you'd loose your evidence.

Contact the organisation that is responsible for the hostel...he may not even hve permission to have the dog on the premises.