Forum Moderators: martinibuster
1. online classifieds without nofollow may well be construed as paidlinks. This may depend on the site and its 'reputation', and whether the links are from a 'relevant' source.
2. bulk links from forums are very 2001, and SEs have been wise to this for years. All reputable SEs have encouraged forums to use nofollow, and if they failed to listen, it is likely that any links emanating from them ave been severely devalued.
Finally, any classified site or forum willing to play these spammy games may well be in a bad neighbourhood, so their links will be worthless; do not under any circumstances link back to sites which operate in this way; or you will put your own site at risk; simply receiving links from spammy sources will not damage your site's ranking (in Google, at least), unless your site is 'part of the scheme'.
But receiving bundles of suspect links may raise a flag over your site, drawing attention to any other matters.
Search engines cannot help but 'notice' bulk linking, and it has to be just a little suspicious, don't you think?
;)
There's nothing wrong with not using 'nofollow', provided the forum mods remove 'non-recommended' links manually; but any forum that does neither is pretty likely to fall foul of sophisticated SEs.
Let's face it, forum spam is neither new nor clever, and SEs deprecate it, and therefore are hardly likely to assign any significant value to links from forums that permit it.
I suspect SEs can easily distinguish between good and bad forums in this respect ;)