Can I use the juice from pickles to make bread?
You don't have to use water as the liquid in your bread. Enriched breads use milk and/or eggs. We have recently had questions about breads which use orange juice. 

On the technical side, you have to adjust recipe a little. Pickle juice doesn't have much dissolved solids, so no need to adjust for that. However, it is very salty, so you should reduce or completely leave out the salt. The acidity will help with gluten development and also with breaking down the starches in flour to make them available for chemical reactions which produce more flavour, so this is a good thing to have. However, yeast itself has some strong pH preferences. It grows best in a slightly acidic environment, but if the dough gets too basic or too sour, it will slow down or not grow at all. I think that the diluted vinegar in the pickle water won't oversour the dough, but it would be a good idea to make the poolish with pure water and only add pickle water for the dough itself. 

As for taste, I can't say that much without ever having tried it, but my intuition says that you will get a whiff of pickles, but not a full-blown taste. After all, bread made with orange juice doesn't taste like biting into an orange. I think you will notice the difference, but you will still have to add pickles to your sandwiches for taste (and they are needed for the crunch anyway). As for horrible, it depends entirely on personal taste. I am not a fan of pickles or soured breads, and wouldn't eat it. There are people who drink the pickle water from the jar; I think they will enjoy the pickle-smelling bread too. If you are a pickle fan, I think it is worth a try, if it doesn't work, you only throw out under a dollar's worth of ingredients.