Never wear socks with sandals. It’s one of those long-standing fashion edicts that seems to have its grounding in a universal understanding of good taste.
…Some might argue it is never acceptable, but even bad taste can be good—if done right.
The trick is to look fashionable enough otherwise to balance the classic dad-on-holiday look. It also requires a willingness to push the boundaries, and to risk getting some sideways glances.