Sometimes a restaurant, bar, hotel, or other attraction has such grave defects that it's just not worth going to. If this is the case, it's best to just leave it out of the destination guide for the place it's in. There's no reason to clutter up a guide with lists of places travellers shouldn't go.
The exception to this rule, however, is when travellers may be led to the attraction by other information sources. For example:
In these cases, write an attraction listing as for places that are recommended, but in the description note that the place isn't worth going to and explain why it should be avoided.
If a destination has only a few reviews (or a few accommodation options), and some are negative, do not delete them — some information is better than none.
Note that comments about unsafe areas under the "Stay safe" section aren't "negative reviews"; they may be important safety information, and are welcome as long as they are sincere and fair comments for the traveler's benefit.