Node reputation is displayed for any node you have voted on or authored.
By default, node reputations are displayed as a single number, e.g., "Reputation: 12".
If you select the "Show reputation spread" option in User Settings, you can sometimes see the up- and down-votes separately, e.g. "Reputation: 12 (+47 -35)".
Occasionally, you may see "Reputation: 12 (no significant downvotes)?"; this indicates that either there were no downvotes or there was an insignificant number of them. You are not shown how many because focusing on the occasional downvote (per node) is usually a mistake. A node having a small number of downvotes usually has more to do with the person(s) doing the voting than with the node. Such downvotes could simply be the result of a mistake, someone having a bad day, someone's pet peeve, etc. Read all about The Role of XP in PerlMonks.
You can toggle the display of "(no significant downvotes)" by clicking the following links. These simply submit your User Settings form with the 'SetNodeTensionQuiet' parameter set to true or false, respectively: