HasTables

public static bool HasTables(this DataSet source) {
	bool lResult = false;
	if(source != null && source.Tables.Count > 0) {
		foreach(DataTable lDtTabla in source.Tables) {
			lResult = (lDtTabla != null && lDtTabla.Rows.Count > 0);
			if(lResultado) break;
		}
	}

	return lResult;
}

DataSet DtSet = new DataSet();
if(DtSet.HasTables()){
	//your code...
}