Agreed. I'm trying to find a good way to manage meta-issues atm, I'm sticking to looking for issues which are definitely unrelated, and commenting on ones which I'm not sure are feasible or entirely relevant, and posting a comment in the meta-issue saying what I do and why (so someone can dispute it or so if I've been over-zealous/unfair).
But merging unrelated issues doesn't help any, if the merged issue gets loads of votes, then LL have to pore over comments in order to work out what people ACTUALLY want from the issue so they can ignore superfluous parts. But how then do they signifiy this has been done? They can't just close/resolve it as that would indicate they did ALL of it which they may not have the resources to do.
Such practises are just messy and stupid, as Meade rightly says, it's only of use for genuinely duplicate bugs with differing symptoms reported.
One thing that annoys me about the JIRA is there seems to be no notification of when things happen to issues you posted, or which you are interested in. Like I had one of mine closed recently with a comment that seemed to have completely misunderstood the problem, but the "My unresolved issues" filter (which I usually use to give a nice overview of things I still want) doesn't show it.
Okay, I think I've spoken about more than just merging

Also, Suzeanne, I noticed a comment by you:
https://jira.secondlife.com/browse/SVC-305In this you're referring to a meta-issue as a 'merged' issue. I hope that isn't what you're referring to? Meta-issues provide a way of grouping issues that is not really suitable for a category. My examples are to group features for privacy, for performance and for small improvements. However, the purpose for these is two-fold, as you'll note performance _is_ a category, but the thing that the meta-issue provides also (hopefully) is a way for people to express a desire to have the meta-issue's topic given greater weight.
To clarify, the improve performance meta-issue allows people to simply say "Yes, I want better performance" and as a result hopefully get more attention by the Lindens to this area. It then also uses the links to provide quick access to a number of features which may help to do this (multi-threading, caching etc.).
If issues linked to them are unrelated then chances are someone has linked it in error, or an attempt to get attention for a feature that does not support the meta issue. Currently I'm trying to keep my own meta-issues tidy, and hope others do the same, but they are a good way for the Lindens to see "Oh, 18 people are voting to improve performance, perhaps we should take a look at some of the ways they think this can be done, or investigate some of our own". And similar for many of the other good meta-issues.