I cannot help but think if someone has done something to their body that they wouldn't want children to see then really they shouldn't show it to any unsuspecting adult either. They I guess if you do something offensive to yourself you don't care who sees it or probably want as many people to see it as possible.

The question is what would that be? People do things to themselves that I just don't understand but that doesn't mean it is wrong or in bad taste it just means I don't get it. 

It seems to me that there is no defining line. What is bad taste to some may be perfectly acceptable to others. Some textiles are horrified by naturism and some think it is definitely not suitable for children, purely based on the idea that genitals are visible. Yet those seem people may think it is OK to allow their children to watch violent films or any number of things that some naturists may find wrong for children.

What textiles or naturists do to themselves is really up to them. Our children tend to talk to us about things that people do to themselves and don't tend to be concerned. Longterm it may normalise it, it may put them off, it may encourage them but it is part of human behaviour and adults and children do have to accept that these differences in tastes and opinions are part of lifes rich tapestry.

If we saw someone with a tattoo that was meant to be offensive -for example racist- then at least it may encourage us to talk to our children about how wrong that is. The real worry is not so much what goes on on people skin (or for that matter with the clothes they chose) but what goes on in side their heads and the actions they then carry out.