Collocations for worthless - adj.

be, feel, prove, seem
become
make sth, render sth
These contradictions made his evidence worthless.

consider sth, discard sth as, dismiss sth as, regard sth as, see sth as
The opinion polls were dismissed as worthless.

absolutely, completely, quite, totally, utterly
almost, nearly, practically, virtually
essentially, largely

to
The diseased plants are worthless to the farmer.

Worthless is used with these nouns:
garbage, rubbish