Just tested your code by printing result to immediate window. It returns True every time.
Code:
Sub Find()
With Selection.Find
.Text = "X-"
.Forward = False
.Format = False
.MatchCase = False
.MatchWholeWord = False
.MatchWildcards = False
.MatchSoundsLike = False
.MatchAllWordForms = False
End With
Debug.Print Selection.Find.Execute
End Sub