Records not stored vertically for decades

Just play the LPS. If it sounds ok, it is ok.

So simple, just ply!.  LPs are not the best audio format, so I do not spend any extra energy with the LPs. Maybe, somebody, emotionally, thinks the LPs very valuable. But, not me, though I do have >2,000 LPs.

Thanks to all those recommending record cleaning methods/equipment cause I’m gonna really need them and am looking into each and every one.  Back in the day I just used the ol’ Discwasher brush/liquid so I’m sure there’s a ton o’ crap lurking in them grooves.  Also definitely gonna get some good rice sleeves so thanks for that tip too.  Think I’m gonna get to see the records tomorrow so I’ll see what I’m dealing with here. 🤞🤞🤞

Always a good idea to clean your LPs, but I see no reason why horizontal storage would make the LPs any more or less in need of a cleaning.  I disagree that even the bottom-most LPs in the pile would have had dirt driven into the grooves to any greater degree than if the LPs had been stored vertically, because the playing surface per se is not supporting most of the weight exerted downward by the stack.  That force will be mostly resisted by the raised lip around the circumference of each LP and to some degree possibly by the label.  The greater possibility for damage is that the topmost LPs might have developed some warps.  But that you can discover for yourself by simply looking; you don't need to be able to play an LP to determine if it is warped.  Someone else already said as much.

@soix As you were informed earlier in the thread that you are the sole investigator of your concerns about quality of the Albums condition.

Your follow up response:

" Ok. I was mainly concerned the pressure from the weight would affect the grooves and the sound but not sounding like that’s much of a problem." 

If the Stack was quite neat, without too much edge overhang of the Albums perimeter edges between tiers, the idea of the Groove receiving compression is one that is less of a concern, as the Outer Raised Dead Wax Rim and Inner Raised Label will have been the points of loading. Hence, references being made to Ring Damage demarcation visible on Album Covers. The Grooves will have been recessed in relation to these two positions and been free from excessive force being applied.

If there has been an increased overhang of the Albums Perimeter Edges between tiers, The Likelihood the Offset in alignment is more that 50 % of the surface area of the Label diameter seems excessive, but the off set being more than the 50 % of the width of the outer Dead Wax, does seem quite viable. If this off set is seen in the stack, there is the likelihood the Grove have been exposed to  point force, where the Dead Wax was able to be compressed and add force to the Groove.

Note: Force applied will be if typical as a Storage, passed through an Albums Outer Sleeve and then the Inner Sleeve, there might even be a Outer Sleeve Protector in use as well. These layers of protection being present, where the point of force is being applied, is certainly an area where an amount of cushioning is also working against the hard / full contact force being exerted to its worst effect.

If the Base the Albums are laying on is perfectly flat then the lower Album should not be exposed to being compressed onto the uneven surface in the area of the Grooves.

As an optimist, I sense the Paper Sleeves may have been exposed to a accelerated deterioration as a result of the environments impact at the storage location. Proper Cleaning Methods will firstly correct any earlier used cleaning methods failings, as well as deal with contaminants from inner Paper Sleeves deterioration being bedded into the groove as well. 

I keep the original Paper Sleeve stored in the Album Cover, but use Anti Static Sleeves to insert the Vinyl into  following the PAVCR Manual Cleaning Method.

Ring Damage to Album Covers is quite likely.

Warping is also a risk. 

The question is when you do get to have hands on the Vinyl LP's once more, are the Storage methods to change, is the new configuration to be that the Albums are to be flipped to the Vertical for the period of storage until you can get to using them regularly ?!!!

Do not overlook that this Album Collection is very likely to be worth a reasonable sum of monies, it can also contain an Album or Two that are much appreciated in value as well.