Bland. That's probably the best description of a poorly made vegetarian dish, to be honest. I often find that if I'm eating one, and I do occasionally, I get a feeling that it's never spicy enough, and a bit plain. I'm always left feeling like there's something missing...well, I guess there is...the meat!
To be fair, a meat dish that is also not well prepared can be a frigging disaster -- undercooked meat is downright dangerous in many cases, and overcooked is dry and unpleasant. But most people are used to cooking it (or at least their favorite cuts), so it's usually not too common to get bland and bad meat (though knowing my fair share of bad cooks, it happened more than just a few times!).
Now, as a vegetarian too, I used to think any dish without meat was also lacking, so I know where you're coming from. My tastebuds (and mentality) changed somewhere along the way though. Now I got to this point where I'll think the opposite, whenever I would eat the meat my BF was about to throw away -- "Meh. It's fine, but my meal really did not need this to taste good".
But I'll also attribute it to the fact that after years of cooking (mostly as a huge meat eater, btw), I know exactly what I like -- spices, herbs, textures, balances of sweet and spicy and sour, all that. So when I cook for myself, I can make it exactly the way I want, meat or no meat, and it's never bland (I mean, I love spicy, so it really never is bland, but that's another story).
Now before drifting further away,
I just came here to say that I had an amazing vegetarian lasagne in a restaurant nearby. I swear, it had just like... two layers or three of pasta, but I think it was two. Spinach, mushrooms, a ton of cheese and béchamel sauce. So fat, cheesy, "full" -- and just a bit of that spicy italian oil on top of it made for a really onctuous and lively mouthful. Yumm! (It tasted in NO way healthy, btw, just delicious)