This study examines how non-target-like formulaic expressions used by advanced second language (L2) speakers of German are perceived by first language (L1) German business professionals in an intercultural workplace setting. By using an experimental design, we explore how L1 business professionals (N = 84) perceive the appropriateness and acceptability of the non-target-like expressions as well as how they perceive the communicative competence of the writer in two conditions: one in which the writer is explicitly described as an L2 user of German (intercultural condition), and one in which the writer is not (German condition). Moreover, by first establishing recurrent unconventionalities when L2 users create their own formulaic expressions (i.e., misspellings, grammatical errors, pragmalinguistic and sociopragmatic infelicities), we examine the effect of the type of unconventionality. Our experimental stimuli are based on authentic student responses to situations in an intercultural workplace setting which were elicited through a written discourse completion task. Our results indicate that in both conditions expressions containing a grammatical error are judged as least acceptable, followed by those with a pragmatic infelicity. Ratings were significantly higher in the intercultural condition, suggesting tolerance of the L1 professionals towards non-target-like expressions of L2 users.