Frozen meat that has gone bad will change in color and texture and can become slimy and have a bad smell to it.
The most common way to know if frozen meat is bad is to smell it and if it's bad it will have a sour smell to the meat.
Meat rarely goes bad as long as it's remained frozen consistently.
The freezing temperatures prevents the meat from growing bacteria and spoiling and meat is usually safe in the freezer for 5 to 10 years and sometimes longer.
But most people will eat the meat well before 10 years time anyway.
As long as you keep the meat frozen it remains safe to eat for a long time but the texture and taste of the meat can change.
As long as the meat has been frozen then the frozen meat can last 1 year to 2 years and sometimes longer depending on the meat.
I have kept meat frozen for longer than a year and it has been okay to eat after all that time.
Meat is still okay to eat well past it's use by or sell by date as long as it's been frozen.
When frozen the meat will not be able to grow bacteria and so it will keep longer because the bacteria cannot grow in the freezing temperatures of a freezer.
Meat will only keep for around 3 to 4 days in the refrigerator while in the freezer it keeps longer.
I have even kept frozen meat such as hamburger, chicken hot dogs etc in the freezer for 5 years and it's been okay to eat.