A dash on an Experian credit report usually signifies no data was reported. If that's in the balance due column, it would be treated the same as a zero, and the only way that I can think of where there might hurt is if all of your revolving credit accounts were reporting $0 or a dash as there is a scoring penalty for using $0 across every one of your accounts. Otherwise, it shouldn't hurt at all, and if they are all dashes or zeroes, it's assumed that the same accounts would be reporting $0 on the other two bureaus causing the same penalty.
It's rare for someone to have the exact score across all 3 bureaus, but I would probably look at other factors.
Different lenders may report different things to each CRA, and each CRA can also handle information reported to them in different ways. Here's an example of one of my cards. The dashes for Last Activity and Terms make no difference in scoring. What matters is the open date, payment status and presence of any lates or delinquencies, balance, and credit limit. As long as it's lumped in with the other revolving credit card accounts, it's treated as such despite what it may say for terms and loan type.
