QTableView has unwanted checkboxes in every cell

Do you by any chance happen to set the Qt::ItemIsUserCheckable flag in flags()?

Try changing MyTableModel::data() to the following:

QVariant MyTableModel::data(const QModelIndex& index, int role) const
{
    if (role == Qt::DisplayRole)
        return "foo";
    else
        return QVariant();
}

Probably the returned QVariant for role Qt::CheckStateRole was misunderstood by the QTableView.