It is not dangerous to make homemade wine in the death-or life sense but the process of making wine can create an inhospitable environment for bacteria causing sickness. However, you can find some things that can ruin a lot of wine; sanitation issue is one of these things.
Headache is the first complaints from homemade wine, drinkers will feel headache the following day. It is because the overabundance of histamines and tannins in the wine. Red wine is known as being full of tannins and you need experience if you want to get a proper balance.
2. Contaminated Materials
You should be aware of that you have to sterilize everything when you use them to contact with the homemade wine, even your fingers. The taste of the wine will be affected if it has any addition of bacteria or contaminant. AS you know, the taste and smell of wine can be similar to vinegar if it is attacked by the smallest amount of bacteria. We cannot change the fact that when bacteria meet oxygen and wine, it will create acetic acid that is able to ruin the homemade wine.