This is something that has been discussed several times, too much
infact. Yes you are correct, the 'bots will not detect this, however
this only works in NS 4+ and IE 3+ in NS 3.x (and there are still
alot of people using it) users will see the pages backround colour (if
set) and all your spamming text... also users who have imamges
switched off will see the same.
Furthermore, you cannont expect it to go un-noticed, when your
competition, or even just someone who doesn't like these techniques
being used (me for example), notices what you have done and reports
it to the Search Engine you can expect to have your listing removed
from their database and the domain name may even be banned, which
would mean you never get a listing again!
My advice, stick to the ligitimate techniques that work, and if your
competition get a better rank than you by using these (and other)
dirty tricks, report them and whatch their site disappear from the
search engine results... its what I do, it works, and you don't run
the risk of penalisation! You have been warned!!!
Hope this helps