Google Link Exchange Criteria

How the sites should be linked?

[webnewton]

A lot has been discussed about link bulding and to whom should we link to and whom not to. I've a question:

1) Let's imagine that someone has a group of 500 sites say on hotels or whatever subject. Now this person starts a few more sites on different topics say on jewellery, shoes, health etc(which is entirely a different category)and he provides links from all the hotels sites to these site. Would Google consider this as spam simply because the two sites belong to different category.
2) Can't a person advertise his one site from another of a diffrent category just because Google would consider it a spam.
3) Anothe question. if this is no problem then what's problem with creating link pages for the purpose of link exchage and linking with sites of differet categories.

Just because Google has formed some criteria for link exchange lately are we barred from advertising sites from other categories?/

[webnewton]

any clue guys