Indeed can you ever delete it? What is the trace you potentially leave behind?

I think pornography is interesting here... one of the biggest uses on the interent, perceived of as anti-social by many and rarely talked about or discussed or 'represented' as information. There are many pieces of software now to enable people to 'mask' their use of porn e.g. proxy IP address etc. [which says something of the embarrassment they feel about the activity and the status of the content]. But to what extent are they truly wiping out any trace - what 'life' does this information have?

Beer in the park. The 'residue' of cans left in the park leaves a trace of the activity that went on there... and I often feel a sense of unease in using the same space because of perceived issues of hygiene and 'dirt'. My kids, however, have no such qualms [the pykies!] and will often pick up cans and play with them before I can intervene - Indeed they're often drawn to those places because of the [rubbish] artfeacts there - they represent sociality and promote curiosity. Fortunately it's not syringes [where I live].