Any animal is natural, so considering good or bad is personal thing. Hinduism states that animals can not be considered as illegible for Heavan. Mahabharata epic is proof for this, when Yudhisthira was asked to leave dog when Indra asked him. That dog was Yama himself, and Yudhisthira denies to come to heavan without dog, Indra told that dog is animal who can only go to hell, There is no place in Heaven for persons with dogs Yudhisthira agrees to go to hell.
SadGurudeva Maharaj Lord Dattatreya is widely famous in Hinduism. Dog was one of the 24 teachers to Dattatreya. In any photograph of Lord Dattatreya , you will find 4 dogs, who are considered as 4 Vedas. There is a story that when Lord Dattatreya speaks, even Vedas keep mum. Vedas originated from breath of Lord Datta. Here you can see even Lord himself respects dogs by learning from them and considers them teachers.
Yamadev, Yamraj or Dharmaraj has a dog with three heads. This is mentioned in Rigveda. The dogs are worshipped as a part of a five-day Tihar festival that falls roughly in November every year. In Hinduism, it is believed that dogs guard the doors of Heaven and Hell.
There is an incranation of shakti whose vehical is dog. Bhairava's vehicle is also a dog.
In Hinduism every creature is considered as originated from Lord Brahma. The properties of animal makes it good or bad for mankind. Actually dogs are the best friends of society but unfortunately worst people are compared with them.
Why dogs can not be kept inside home?
Dogs may have many diseases which are allergetic to humans. Natural environment is more suitable to animals.
According to Hinduism, dogs are guards, and guards are at entrance only, there is no place for them inside home.