Sodom and Gomorrah, and their surrounding cities gave themselves to promiscuous indulgence of lusts, and WENT AFTER STRANGE FLESH.

Promiscuous indulgence of lusts span masturbation, sleeping with the same sex, sleeping with corpse, pedophile, adultery,orgies, sex outside marriage contract.

But going after strange flesh is another level.
It is having sex with anything but mankind.

And God showing disapproval, rained on them fire, setting an example, for those who would live likewise, if they choose not to repent.
For there is no respecter of persons with God.
These things are not pleasing to The Lord.
That's why the believers in Christ( the ones who believe He is Christ, and that He died for their sins) are told to live their lives pleasing to the Lord.
Because before His judgement seat, we shall receive judgements on what we have done in our life of pilgrimage. Either good or bad.
The bad ones, will be told to depart. The good ones will be welcomed in.
2 Corinthians 5 : 9 - 10.
Matthew 7 : 22 - 23

These acts mentioned in Jude 7, defiles the flesh.

You know what defile means?
It means contaminate.
Romans 1 : 27

Not only is this act frowned against by the Lord Jesus in His church, because it is an error, but it also destroys the natural strength of the flesh.
It pollutes it, weakening it's strength.
And some of the animals in the act of bestiality are also sold, and are ate.
And we wonder why, it seems we don't have a long life span.