We have three hydrangea bushes. We didn't trim the dead sticks on them because of so many stories being told to us saying yes, trim them back because it will help them bloom more; and no because the dead ones are what makes them bloom. I'm also told if you don't it drinks the juice from the plant. So could somebody give me the actual answer please?
Hmm, an interesting collection of misinformation! It depends what variety of Hydrangea, is the answer - if you have Hydrangea macrophylla (those with large, mophead flowers or lace cap flowers), you don't cut those until growth begins in spring. When you see new shoots, that's the time to trim off dead flowerheads from the previous year, along with dead bits of stem, but other than that, any further cutting back will reduce flowering. The reason for not deadheading is the spent, dead flowerheads provide a little more protection for the upper parts of the plant in cold weather during winter. Some images of Hydrangea macrophylla types here
If you have Hydrangea paniculata (or any of its varieties, usually cone shaped flowers), they can be deadheaded after flowers are finished if you want - they can also be pruned right down in Fall (autumn) and they'll still flower the following year. Conversely, if you did that with a macrophylla type, you wouldn't get any flowers at all the next year. An example of a paniculata type shown in the link below - in this case, its Hydrangea paniculata 'limelight' but it does show the difference in shape of the flowers
Then there's the climbing ones such as Hydrangea anomala - these are usually left to their own devices, although spent flowers can be removed in spring, left until then for reasons similar to macrophylla - more cold protection, but in milder regions, you can remove them after flowering.
You haven't said what variety of Hydrangeas you have, but hopefully you can work it out from this answer.