What do Lhosts look like

Are they indistinguishable from base humans or are there tells that give away a body’s biosynthetic nature?

It depends on the model, and alterations. A standard lhost will be nearly indistinguishable from a baseline human, possibly freer of flaws. Older “antique” lhosts may move in a not quite fully fluid manner more due to the host not fully intergrating rather than a visible flaw, “Standard” lhosts are practically indistinguishable from baseline human, any minor differences can be passed off as augmentation. Siren lhosts are beyond natural and would be detectable as either the most beautiful supermodels at a glance or correctly identified as a lhost after any real inspection revealed the perfect symmetry and balance. Most of the other lhosts are enhanced far enough for even a cursory glance to reveal them as lhosts suited for environmental or combat conditions. There will be further exceptions where they will pass as a normal human, proxies or infiltration models will spend more effort on disguise rather than enhancement.

To make a long story short your average resurrected human will be indistinguishable unless demonstrating enhanced strength or the like, possible moving weirdly if only just resurrected or in an antique model. On the other hand most specialist and Aspect models will be identified by anything more than a casual look.