My timing chain cover does not use a solid gasket, instead it relies on gasket maker, which is caulk-like paste. The cover is fastened by something around 20 bolts. I am curious how bad can it be if the gasket maker gets in some of the holes, impeding the bolt grip/torque.
It is not going to bother it too badly. It can cause issues if you get too much into a hole. As was already stated, this can cause breakage of the block. It's called hydraulicing. I don't think you could get enough torque on these smaller bolts you are talking about to cause you any issues as the bolt would break off before it would get that tight. I have never worried about there being a small amount in this type of application. It's mainly a problem with larger bolts such as head bolts which can stand a lot more torque. Also, it doesn't usually happen with gasket maker, but if you have too much oil in the hole it can surely happen (with the larger bolts).
Basically, what happens is you have filled in the bolt hole with the liquid. When you put the bolt into the hole and force it down, the liquid does not compress, so the pressure has to go somewhere. It will find any avenue it can, so can possibly cause problems.
In some instances you want to have sealant in the holes. Holes in the block which enter into the water jacket need to be sealed. The only way you can do this is with sealant (place a small amount on the threads so it encompasses the entire bolt). This does not affect the torque of the bolt to any great extent, so there is no issue there either.