Unseelie Seelie Fey

[Zanos]

The issue is specific to templates, which often say to use the base creatures statistics if not otherwise noted. That would include level adjustment, however, MM1 says this about LA in general:

Level Adjustment
This line is included in the entries of creatures suitable for use as player characters or as cohorts (usually creatures with Intelligence scores of at least 3 and possessing opposable thumbs).

So if a monster doesn't have an LA listed, it's not suitable for use as a PC. A template that makes no mention of LA though is fair game if applied to a base creature that does have one.

3.0 material however specifically requires updates to be used with 3.5, so if you're trying to use a 3.0 template and saying it has +0 LA, your DM is likely to disagree.