The phrase "open to suspicion" can have a negative connotation, as it implies that something or someone is potentially involved in something unsavory or unsatisfactory. There are many different synonyms or similar phrases that could be used in place of "open to suspicion" to convey a similar meaning. Some examples include "questionable," "dubious," "suspect," "unclear," "ambiguous," "doubtful," "inconclusive," "undetermined," and "debatable." Depending on the context, each of these words could be an effective replacement for "open to suspicion," and could help communicate a more nuanced or precise meaning.