The heuristic of information processing fluency plays an important role in making judgments. Some sources of processing fluency can be relevant or irrelevant to the content of a judgment. In this study, we aim to check whether individuals can distinguish different sources of fluency or fluency has a general effect on judgments. We used an artificial grammar learning paradigm (AGL) and tested the effects of different fluency sources (grammaticality and perceptual noise) on the judgment of grammaticality or of subjective ease of reading. It was found that both grammaticality and perceptual noise affected grammaticality judgements: the grammatical and the less noisy strings were evaluated more often as grammatical. However, only the perceptual noise affected judgments of subjective ease of reading. The results obtained provide evidence that fluency may contribute to the effects of implicit learning. It is possible that the processing fluency heuristic is the additional factor of judgement in the lack of explicit knowledge. Perhaps, perceptual noise provided almost complete explicit information for judgment of ease of reading; hence there was no need for additional heuristics. Another possible explanation is that perceptual fluency sources affect the early stages of information processing in a mandatory manner, unlike the conceptual ones. Overall, results are better explained by the non-specificity fluency hypothesis supporting the impossibility to distinguish between different fluency sources.