garbage in, garbage out
used to say that if the data (=information) you put into a computer is bad, the results you get back will be bad, even if the computer program you use works properly

[TahlilGaran] Dictionary of Contemporary English ▲

Garbage in, garbage out.
[mainly American]
something you say which means that something produced from materials of low quality will also be of low quality.
The meals are pretty poor but then they never use fresh ingredients - garbage in, garbage out.

[TahlilGaran] English Idioms Dictionary ▲