Arginine side chain contains a guanidinium group therefore this amino acid has properties comparible with those of guanidinium chloride (solubilizing effect preventing aggregation).
Arginine very infrequently, if ever, actually serves to denature proteins, rather it seems to offer hydrogen bonding to denatured protein side chains. These interactions seem to lessen as the protein folds and the arginine is excluded, allowing the proteins to refold without aggregation caused by H bonding. It seems to have very little effect on disulfide formation and these cross links can lead to aggregation that Arg cannot perturb.