So I’ve been told for quite a while that tris in a model are bad but if a game engine triangulates everything anyway then why are they a problem?
Matt
Whoever told you that hasn’t got a clue, unless they were talking about triangle count.
They don’t subdivide cleanly and can cause very ugly problems with animated meshes so they aren’t good news if you wish to, say, create high poly versions of your models for sculpting or just animating in general
Don’t worry you can recombine into quads in Blender. Since 2 tris always combine to one quad in a good model the odd tri that can’t be combined with another tri is a since of patchy and poor modeling: a sign of poor mesh topography.
Okay thanks! 
Can you automatically recombine them?
Oh wait nevermind I found the hotkey haha 
Thanks for the info
Tris are only bad if you’re going to be smoothing the model. You want your highpoly to be all quads if possible, your low poly (the model that’s going into the game) can be a combination of quads and tris. That being said, it’s usually easier to work with quads, and only create tris to optimize the model.
While working with a deformable mesh, you should develop a desire to keep loops of vertices along nicely flowing paths. If you have loops going around the arm, and a loop going all the way down the arm, then the bone deformations will behave more predictably and nicely. The best way to keep these orderly chains of vertices is to use only quads. Intersections at the vertices should have four edges, not three or five or more. When you subdivide or add a “subdivision surface” all the quads become more quads that don’t break the loops. And so on.
But yes, once you actually hand these quads over to a piece of hardware, it’s really all just triangles. Modeling apps are more about manipulating the data, so clean loop topology is good. Some engines like Unity’s are oriented toward handing data to the hardware, more than manipulating the data, so they just ignore the quad thing altogether and design all the mesh handling code around triangles.
You’ll notice them if they’re on a character model or something. Edges are what define the shape of an object and if you have a bunch of quads and suddenly a tri is modelled in there it will distinctly change that edge shape or silhouette. Thats a bad thing, you will pretty much always get a better, more controlled result (especially during work/manipulation) with quads.
The engine is going to translate them as tris, but think of the quads as the actual shape and outer silhouette. The tri basically just bridges two corners of the quad and is one of the reasons that there is a Turn Edge tool - so you can force the interior edge of a quad to go across either corner if need be but thats generally a sign that you need more polys.
Look at 3d scanning for example, its total crap for topology unless you just have a bajillion polys to manipulate and cant see the pointy edges.
Plus its a mess for animating, but much of that is mentioned above.
Two videos that help illustrate why you’d want to use quads.
But it only matters for subdivisions anyway. And even then, tris will subdivide into smaller quads in the end. Though there will be “splits” in the flow, but it’s unimportant for static objects as long as the surface stays even over the area.
It is quite a hassle for an artist to try to make some arbitrary shape into quads and eats extra time at modelling stage. But I guess it is getting mandatory as a pre-stage before Zbrushing/Mudboxing. I’ve noticed that all-quad modelling tend to shy away into models with pretty simple shaping - combos of cylindrical and box-like structures. In a way that in itself impedes creativity, but since the intricate details are post-added in Zbrush maybe it’s not a big deal.
Yes, it’s like how many slivers of pie can you slice?
Tris subdivide into tris, not quads, its not clean at all and it wont take long in zbrush before you’re cursing at it. The workflow with zbrush/mudbox is, model out a base model in max/maya etc, low poly, all quads, closely following the shape of what you wish to model. Take it into sculpting app and sculpt away. By the end of the sculpt your model will probably look absolutely nothing like your base mesh, so you dont use the base mesh anymore, you use the packages tools or something like topogun to retopologise your model, which is much like drawing a new skin over your sculpt that follows it closely (at this point quads and tris matter a bit less, but a base mesh with tris is problematic). You’d use the new retopologised model and the sculpt to bake out your normal maps etc for the final asset.
Topology.
Yes, I know the process, I’m an artist 
And no, you’re wrong, tris subdivide into quads, try it out in 3D Studio Max, imagine three quads meeting with one of their corners in the triangle centroid.
@halley nodes with 3 or 5 are totally acceptable branches or splits in good topology. In fact, how can you achieve good topology without them? … More than five are considered bad yes …
EDIT picture added … model by Jonathan Williamson :
When going too lowpoly you might want to manually ‘cut’ non planar quads the way you see necessary, to ensure the best silhouette.
Otherwise it’s going to be “random” depending on what software you’re using… and sometimes the software will cut the quads precisely the way you didn’t want, don’t let this happen!
When you’re on a triangle budget, triangles are your friends. (Use them wisely)
Remember once the mesh gets to unity, it’s 100% triangles anyway. (Not sure how it works with DX11 tessellation though)
But still… you want to avoid triangles when modelling, or doing retopo, in the sense you want a good topology flow. You want nice loops that don’t go in spirals, avoid N-Gons and all that stuff.
An irregular topology is bad for shading… even with normal maps, it’s important that the vertex shading underneath looks nice.
Also, as mentioned, good topology is important for character deformation.
Sorry i’d been awake a long time and i think i was only reading every 5th word of a post. Reading back over i dont think i read your post properly at all, feel a bit of a dick now, but i will add that you’re right, you’re very likely heading for zbrush if youre modelling like that anyways, so i’ll claw that back, ha! And if tris subdivide into quads then i have definitely been away from invested modelling for too long, and i have! Being a bad programmer instead has consumed all my time aha