A range of theories that are properly counted as scientific cannot be falsified at present and quite possibly never (eg Hugh Everett's Many Worlds Interpretation).   However what can be done is to seek alternative explanations which deal with the anomalies involved more satisfactorily.

If this can be done the credibility of the theories involved are reduced, if it cannot be done, the credibility is strengthened. That involves critical analysis. The suggestion that critical analysis which reduces the credibility of a fallacious theory at the same time gives it greater credibility is hard to sustain.